No login page / access outside of LAN, PING6 = OK, SSL-Test = OK

Nextcloud version: 16.0.3
Operating system and version: Ubuntu 18.04.3 LTS
Apache: Server version: Apache/2.4.29 (Ubuntu)
PHP version: PHP 7.2.19-0ubuntu0.18.04.1 (cli)
Running on Odroid-N2

Parallel running: Pi Hole including DNS server

I am not able to see the login page from outside the LAN. Error message of browser is “ERR_EMPTY_RESPONSE”. I am using a dynDNS service (dynv6.com) and regularly update the ipv6 (extraction by ip -6 addr list scope global mngtmpaddr $device | grep -v " fd\|fe" | sed -n '/:8a12:dd8e:fb02:5b00/!d;s/.*inet6 \([0-9a-f:]\+\).*/\1/p') to the dynDNS service with their script. Fritzbox is set up to pass through traffic to the Ordoid-N2. Ping ipv6 test with dyndns domain was successful on subnetonline.com. SSL test ssllabs.com/ssltest was also succesful, however, it showed “this server does not support Forward Secrecy with the reference browsers. Grade capped to B”.

Within the LAN Nextcloud works fine.

The Nextcloud app on android 5.0 says “SSL initialization failed” outside the LAN and “access over a non-trustworthy domain” within the LAN .

Is this the first time you’ve seen this error? No, I assume access from outside the LAN has never worked but was unnoticed.

The output of nextcloud.log:

{"reqId":"ZVFoWM6Y4KTkRAiCx5kh","level":0,"time":"2019-08-10T17:59:38+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Finished OCA\\Federation\\SyncJob job with ID 18 in 0 seconds","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"uPkcokbJ9CjzkBI0LGwo","level":0,"time":"2019-08-10T18:09:40+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"QyEoTlhkBdpHJPABJe8Z","level":0,"time":"2019-08-10T18:21:42+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"QhP2Bf3k4yRT9MGV3Btu","level":0,"time":"2019-08-10T18:36:52+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"bLRT8TWuG8qlKBmeelnY","level":0,"time":"2019-08-10T18:49:40+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"uOUVJFiNop3bSL3v2HvB","level":0,"time":"2019-08-10T19:01:58+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"YyGZvzqeQPqaIZDNxhoh","level":0,"time":"2019-08-10T19:14:40+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"bDWNhBNBQpLgDhbhXXiL","level":0,"time":"2019-08-10T19:27:41+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"1ZzTDQDLGrzw5ERm5PlY","level":0,"time":"2019-08-10T19:40:42+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"bwGa2fh9pt7zu1cBMcfI","level":0,"time":"2019-08-10T19:51:46+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"b8E078ByvnKsXOx1a1RS","level":0,"time":"2019-08-10T20:06:11+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"npZrD4cMFZxUbxteCnBx","level":0,"time":"2019-08-10T20:19:40+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"41Y5yOxhMfPn0AMm3zb3","level":0,"time":"2019-08-10T20:30:49+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Run OC\\Authentication\\Token\\DefaultTokenCleanupJob job with ID 19","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"41Y5yOxhMfPn0AMm3zb3","level":0,"time":"2019-08-10T20:30:49+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Invalidating session tokens older than 2019-08-09T20:30:49+00:00","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"41Y5yOxhMfPn0AMm3zb3","level":0,"time":"2019-08-10T20:30:49+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Invalidating remembered session tokens older than 2019-07-26T20:30:49+00:00","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"41Y5yOxhMfPn0AMm3zb3","level":0,"time":"2019-08-10T20:30:49+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Invalidating session tokens older than 2019-08-09T20:30:49+00:00","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"41Y5yOxhMfPn0AMm3zb3","level":0,"time":"2019-08-10T20:30:50+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Invalidating remembered session tokens older than 2019-07-26T20:30:50+00:00","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"41Y5yOxhMfPn0AMm3zb3","level":0,"time":"2019-08-10T20:30:50+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Finished OC\\Authentication\\Token\\DefaultTokenCleanupJob job with ID 19 in 1 seconds","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"41FOVeVpd3CSN8n05twM","level":0,"time":"2019-08-10T20:32:41+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"qThHOEWrQ9qxaBc86FXx","level":0,"time":"2019-08-10T20:43:40+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"MYXgmsLZ4XBs6XZEkaXR","level":0,"time":"2019-08-10T20:49:49+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Run OC\\Log\\Rotate job with ID 20","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"MYXgmsLZ4XBs6XZEkaXR","level":0,"time":"2019-08-10T20:49:49+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Finished OC\\Log\\Rotate job with ID 20 in 0 seconds","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"xQ03T5kOKpeRVBUaS1h3","level":0,"time":"2019-08-10T20:55:41+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"InG08eL9ah45qZu28SQZ","level":0,"time":"2019-08-10T21:09:43+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"9sCuQNAHSKWrUlJxwCPn","level":0,"time":"2019-08-10T21:17:50+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Run OC\\Preview\\BackgroundCleanupJob job with ID 21","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"9sCuQNAHSKWrUlJxwCPn","level":0,"time":"2019-08-10T21:17:50+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Finished OC\\Preview\\BackgroundCleanupJob job with ID 21 in 0 seconds","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"AFZSpuLRCXbGvmWDf1lM","level":0,"time":"2019-08-10T21:17:58+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Run OCA\\Files\\BackgroundJob\\DeleteOrphanedItems job with ID 2","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"AFZSpuLRCXbGvmWDf1lM","level":0,"time":"2019-08-10T21:17:58+00:00","remoteAddr":"192.168.178.30","user":"--","app":"DeleteOrphanedItems","method":"GET","url":"\/cron.php","message":"0 orphaned system tag relations deleted","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"AFZSpuLRCXbGvmWDf1lM","level":0,"time":"2019-08-10T21:17:58+00:00","remoteAddr":"192.168.178.30","user":"--","app":"DeleteOrphanedItems","method":"GET","url":"\/cron.php","message":"0 orphaned user tag relations deleted","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"AFZSpuLRCXbGvmWDf1lM","level":0,"time":"2019-08-10T21:17:58+00:00","remoteAddr":"192.168.178.30","user":"--","app":"DeleteOrphanedItems","method":"GET","url":"\/cron.php","message":"0 orphaned comments deleted","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"AFZSpuLRCXbGvmWDf1lM","level":0,"time":"2019-08-10T21:17:58+00:00","remoteAddr":"192.168.178.30","user":"--","app":"DeleteOrphanedItems","method":"GET","url":"\/cron.php","message":"0 orphaned comment read marks deleted","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"AFZSpuLRCXbGvmWDf1lM","level":0,"time":"2019-08-10T21:17:58+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Finished OCA\\Files\\BackgroundJob\\DeleteOrphanedItems job with ID 2 in 0 seconds","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"FMIW4npBGOge5TWosGbr","level":0,"time":"2019-08-10T21:18:24+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Run OCA\\Files\\BackgroundJob\\ScanFiles job with ID 1","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"FMIW4npBGOge5TWosGbr","level":0,"time":"2019-08-10T21:18:24+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Finished OCA\\Files\\BackgroundJob\\ScanFiles job with ID 1 in 0 seconds","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"TgpBqAhCayMYryKCTzY9","level":0,"time":"2019-08-10T21:18:51+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Run OCA\\Files\\BackgroundJob\\CleanupFileLocks job with ID 3","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"TgpBqAhCayMYryKCTzY9","level":0,"time":"2019-08-10T21:18:51+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Finished OCA\\Files\\BackgroundJob\\CleanupFileLocks job with ID 3 in 0 seconds","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"tNJ767MJ7T8fWFu3E2DW","level":0,"time":"2019-08-10T21:18:55+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Run OCA\\DAV\\BackgroundJob\\CleanupDirectLinksJob job with ID 5","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"tNJ767MJ7T8fWFu3E2DW","level":0,"time":"2019-08-10T21:18:55+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Finished OCA\\DAV\\BackgroundJob\\CleanupDirectLinksJob job with ID 5 in 0 seconds","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"qzA7Y8DpfR5tCnTW6esw","level":0,"time":"2019-08-10T21:19:17+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Run OCA\\DAV\\BackgroundJob\\UpdateCalendarResourcesRoomsBackgroundJob job with ID 6","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"qzA7Y8DpfR5tCnTW6esw","level":0,"time":"2019-08-10T21:19:17+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Finished OCA\\DAV\\BackgroundJob\\UpdateCalendarResourcesRoomsBackgroundJob job with ID 6 in 0 seconds","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"mF4XtpImDtkjTv3fpyl4","level":0,"time":"2019-08-10T21:19:34+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Run OCA\\DAV\\BackgroundJob\\CleanupInvitationTokenJob job with ID 7","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"mF4XtpImDtkjTv3fpyl4","level":0,"time":"2019-08-10T21:19:34+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Finished OCA\\DAV\\BackgroundJob\\CleanupInvitationTokenJob job with ID 7 in 0 seconds","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}

The output of your config.php file in /var/www/html/nextcloud/config/config.php:

<?php
$CONFIG = array (
  'instanceid' => 'ocv0m0omokbn',
  'passwordsalt' => 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx',
  'secret' => 'XU/xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx',
  'trusted_domains' => 
  array (
    0 => 'xyz.dynv6.net',
  ),
  'datadirectory' => '/var/www/html/nextcloud/data',
  'dbtype' => 'mysql',
  'version' => '16.0.3.0',
  'overwrite.cli.url' => 'https://xyz.dynv6.net',
  'dbname' => 'nextcloud',
  'dbhost' => 'localhost',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'dbuser' => 'nextcloud',
  'dbpassword' => 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx',
  'installed' => true,
  'mysql.utf8mb4' => true,
  'maintenance' => false,
  'memcache.local' => '\\OC\\Memcache\\APCu',
  'theme' => '',
  'loglevel' => 0,
  'updater.secret' => '$xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx',
);

The output of your Apache log in /var/log/apache2/error.log:

2600:c02:1020:4202::ac10:826b - - [10/Aug/2019:23:12:08 +0200] "GET /index.php/login HTTP/1.1" 200 17370 "-" "Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Firefox/45.0"
2600:c02:1020:4202::ac10:826b - - [10/Aug/2019:23:12:11 +0200] "GET /?SSL_Labs_Renegotiation_Test=User_Agent_May_Not_Show HTTP/1.0" 400 3139 "-" "-"
192.168.178.30 - - [10/Aug/2019:23:12:24 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 979 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:12:36 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 979 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:12:53 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 979 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:13:06 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 979 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:30:34 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 979 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:30:55 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 979 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:31:04 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 979 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:31:26 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 4091 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:31:34 +0200] "GET /index.php/csrftoken HTTP/1.1" 200 1151 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:31:34 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 979 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:31:55 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 979 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:32:04 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 979 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:32:26 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 979 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:32:34 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 979 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:32:56 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 979 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:33:04 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 979 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:33:26 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 979 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:33:34 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 979 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:33:56 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 979 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:34:04 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 979 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:34:26 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 979 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.30 - - [10/Aug/2019:23:34:34 +0200] "GET /ocs/v2.php/apps/notifications/api/v2/notifications HTTP/1.1" 200 979 "-" "Mozilla/5.0 (Windows NT 6.1; rv:68.0) Gecko/20100101 Firefox/68.0 anonymized by Abelssoft "
192.168.178.29 - xyz-admin [10/Aug/2019:23:34:39 +0200] "GET /index.php/204 HTTP/1.1" 204 4567 "-" "Mozilla/5.0 (Android) ownCloud-android/3.6.0"
192.168.178.29 - xyz-admin [10/Aug/2019:23:34:39 +0200] "GET /index.php/204 HTTP/1.1" 204 4571 "-" "Mozilla/5.0 (Android) ownCloud-android/3.6.0"
192.168.178.29 - xyz-admin [10/Aug/2019:23:34:39 +0200] "PROPFIND /remote.php/webdav/ HTTP/1.1" 207 1051 "-" "Mozilla/5.0 (Android) ownCloud-android/3.6.0"
192.168.178.29 - xyz-admin [10/Aug/2019:23:34:39 +0200] "GET /index.php/204 HTTP/1.1" 204 1432 "-" "Mozilla/5.0 (Android) ownCloud-android/3.6.0"
192.168.178.29 - xyz-admin [10/Aug/2019:23:34:40 +0200] "PROPFIND /remote.php/webdav/Dokumente/ HTTP/1.1" 207 1042 "-" "Mozilla/5.0 (Android) ownCloud-android/3.6.0"

The output of Virtual Host /etc/apache2/sites-available/001-nextcloud.conf:

<VirtualHost *:80>
ServerName xyz-offsite.dynv6.net

ErrorLog ${APACHE_LOG_DIR}/error.log
CustomLog ${APACHE_LOG_DIR}/access.log combined

Redirect permanent / https://xyz-offsite.dynv6.net
</VirtualHost>

<IfModule mod_ssl.c>
SSLStaplingCache shmcb:/tmp/stapling_cache(128000)
<VirtualHost *:443>

ServerName xyz-offsite.dynv6.net

<IfModule mod_headers.c>
Header always set Strict-Transport-Security "max-age=15552000; includeSubDomains"
</IfModule>

DocumentRoot /var/www/html/nextcloud

ErrorLog ${APACHE_LOG_DIR}/error.log
CustomLog ${APACHE_LOG_DIR}/access.log combined

# SSL Konfiguration
SSLEngine on
SSLCertificateFile /etc/letsencrypt/live/xyz-offsite.dynv6.net/fullchain.pem
SSLCertificateKeyFile /etc/letsencrypt/live/xyz-offsite.dynv6.net/privkey.pem
SSLProtocol All -SSLv2 -SSLv3 -TLSv1.1

<FilesMatch "\.(cgi|shtml|phtml|php)$">
SSLOptions +StdEnvVars
</FilesMatch>
<Directory /usr/lib/cgi-bin>
SSLOptions +StdEnvVars
</Directory>

#Nextcloud Konfiguration
<Directory /var/www/html/nextcloud/>
Options +FollowSymlinks
AllowOverride All

<IfModule mod_dav.c>
Dav off
</IfModule>

SetEnv HOME /var/www/html/nextcloud
SetEnv HTTP_HOME /var/www/html/nextcloud
</Directory>

</VirtualHost>
</IfModule>

Hi,

Your logs show no access by an IPv6 address. Looks like traffic is not coming through.
Can you access your server (see at least an NC error message) when you use its IPv6 address locally? (http://[ipv6-address]/nextcloud/)

In your FritzBox you defined the “port forwarding” for IPv6, right?
Is your FritzBox reachable from the outside via HTTPS (for configuration purposes)? If so, could you check you defined a different port for accessing your FB’s web GUI? I’m even not sure if this has to be done in general - I did it for some reason in the past and now my FB’s web GUI is only reachable from a port 48443 - even from local network. Maybe something worth trying.

With http://[fd00::8a12:dd8e:fb02:5b00] within the LAN, no login page shows up either. With ipv4, the login page does show up.

Nextcloud.log:

{"reqId":"Ohd21ozpiTQOWbSOWW6d","level":0,"time":"2019-08-10T22:16:29+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Finished OCA\\UpdateNotification\\ResetTokenBackgroundJob job with ID 22 in 0 seconds","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"V6y0aak2q58S3BwerAMH","level":0,"time":"2019-08-10T22:16:39+00:00","remoteAddr":"192.168.178.30","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/dav\/files\/xyz-admin\/Dokumente\/Vertr%C3%A4ge\/Ergo%20Direkt","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"j3Dp70MKa9Rr4TGixAQq","level":0,"time":"2019-08-10T22:21:21+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"75qxug9Si9kMR9c4kdZT","level":0,"time":"2019-08-10T23:05:06+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"ncM201UHmnfj080yc7iH","level":0,"time":"2019-08-10T23:22:06+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"RjMJzL8TuAcbeeFY8LUi","level":0,"time":"2019-08-10T23:35:37+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"onCtOJ9QITy6pDEfDmWe","level":0,"time":"2019-08-10T23:47:41+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"qNaQfebdgBqPK3Gsnq3c","level":0,"time":"2019-08-11T00:00:42+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"GPutgQpyteSQU01yAyXi","level":0,"time":"2019-08-11T00:14:40+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"mY6b8W8H3PljlZ2viHNi","level":0,"time":"2019-08-11T00:27:41+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"8KI49wP7XlGHDf4Maqqh","level":0,"time":"2019-08-11T00:39:40+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"w2sMZaALBJFnHU6ipNdX","level":0,"time":"2019-08-11T00:54:41+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"7SgLQuXaqWaajnnHYSKS","level":0,"time":"2019-08-11T01:07:42+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"82h8FvNGSiPshzGblUwz","level":0,"time":"2019-08-11T01:20:42+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"afLPP8CFZS02dA4lvY1w","level":0,"time":"2019-08-11T01:37:41+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"8sbKbvbiRIo5gBWFmad7","level":0,"time":"2019-08-11T01:50:43+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"uZXDRa1p6IBqcc750NSV","level":0,"time":"2019-08-11T02:05:52+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"TPtNUCOGdnJ5Me1Yrqmh","level":0,"time":"2019-08-11T02:20:03+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"mNvoJJpqaMGnIz76rwYG","level":0,"time":"2019-08-11T02:31:16+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"KDOy2lhpu76u3JO3f7hO","level":0,"time":"2019-08-11T02:42:58+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"0cWQRmROClKb6iCmQY3n","level":0,"time":"2019-08-11T02:54:40+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"raemgH2CHApgpizAfSHZ","level":0,"time":"2019-08-11T03:09:50+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"Kr664fa0tWHywIBdBQEi","level":0,"time":"2019-08-11T03:31:45+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"edCtCKxOZPuWj9yb9Tkq","level":0,"time":"2019-08-11T03:44:50+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"lclB20XCtdqR1QkwR7X2","level":0,"time":"2019-08-11T03:59:40+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"lpwoWswWCG6y1so3Fj92","level":0,"time":"2019-08-11T04:10:17+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"vypN9UrzGDwwVjZ4ct2t","level":0,"time":"2019-08-11T04:22:42+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"P2MisHnPZzdMfHZ3V72Y","level":0,"time":"2019-08-11T04:35:44+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"aycGBEqHfbNn6iEjFy1f","level":0,"time":"2019-08-11T04:48:48+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"iQT9bbgxNavXou9FhuAk","level":0,"time":"2019-08-11T04:59:40+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"10qr5W7xeJ2w70PDGKKg","level":0,"time":"2019-08-11T05:14:43+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"VEzrD7zsHNYeVIFrJoUj","level":0,"time":"2019-08-11T05:26:49+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"vBg3hwxW5IzpsS5RQSXL","level":0,"time":"2019-08-11T05:39:40+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"4yOnw2XpzF2yKbkRFxE5","level":0,"time":"2019-08-11T05:52:42+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"6A6Hn6eQ6lDuHb7V67dt","level":0,"time":"2019-08-11T06:04:40+00:00","remoteAddr":"192.168.178.29","user":"xyz-admin","app":"no app in context","method":"PROPFIND","url":"\/remote.php\/webdav\/Dokumente\/","message":"hiding hidden file .stfolder","userAgent":"Mozilla\/5.0 (Android) ownCloud-android\/3.6.0","version":"16.0.3.0"}
{"reqId":"Gs5NR7nVqLL9fWRcz2ro","level":0,"time":"2019-08-11T06:20:02+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Run OC\\Core\\BackgroundJobs\\CleanupLoginFlowV2 job with ID 28","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"Gs5NR7nVqLL9fWRcz2ro","level":0,"time":"2019-08-11T06:20:02+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Finished OC\\Core\\BackgroundJobs\\CleanupLoginFlowV2 job with ID 28 in 0 seconds","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"HZ6W9Cmn9aohxxTztPNP","level":0,"time":"2019-08-11T06:20:29+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Run OCA\\Files_Sharing\\DeleteOrphanedSharesJob job with ID 13","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"HZ6W9Cmn9aohxxTztPNP","level":0,"time":"2019-08-11T06:20:29+00:00","remoteAddr":"192.168.178.30","user":"--","app":"DeleteOrphanedSharesJob","method":"GET","url":"\/cron.php","message":"0 orphaned share(s) deleted","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}
{"reqId":"HZ6W9Cmn9aohxxTztPNP","level":0,"time":"2019-08-11T06:20:29+00:00","remoteAddr":"192.168.178.30","user":"--","app":"cron","method":"GET","url":"\/cron.php","message":"Finished OCA\\Files_Sharing\\DeleteOrphanedSharesJob job with ID 13 in 0 seconds","userAgent":"Mozilla\/5.0 (Windows NT 6.1; rv:68.0) Gecko\/20100101 Firefox\/68.0 anonymized by Abelssoft ","version":"16.0.3.0"}

No. In the beginning I gave the FB my login details to the dyndns provider, the FB gave the ipv6 of the FB to the DynDNS provider and the ping test to the Odroid-N2 was unsuccessfull. Then, I switched the DynDNS feature in the FB off and started updating the dyndns provider with the ipv6 of the Odroid-N2 by using this script of the dyndns provider: https://gist.github.com/corny/7a07f5ac901844bd20c9 , I had to fuddle around with the script so that the script picks the “right”(?) ipv6 (ending with 8a12:dd8e:fb02:5b00, see my first post in this thread) from the command ip -6 a. Ping test worked (see my first post in this thread).

clpDD4D

clp3A9B

Hi,
In your FritzBox set the option to only assign ULA when there is no internet connection.
In addition make sure you really discovered the global scope IPv6 of your device. Just mentioning that the FritzBox doesn’t always show the correct global scope address for the devices in the overview.
Me and a friend of mine had to enter the correct address manually for the port forwarding in the FB as it picked the wrong address for some reason.
Maybe that’s why you thought the script picked the “wrong” one?

If that all does not help, could you send me the hole output of

ip addr

and your dyndns via private message?

For everyone stumbling across this issue:
There was no issue with the router (FritzBox) or server configuration, the problem was the client side, having an IPv4 internet access only.
While @Piezo’s server uses a Dual Stack Light internet access, it can only be reached by its IPv6 address. The router’s external IPv4 address is not reachable from the outside (because DS Lite/ NAT).

With the server only reachable via IPv6 it means that clients need to have an IPv6 internet access as well (“DS” or “DS Lite only” doesn’t matter on the client side; but there has to be one IPv6 address).

Unfortunately the VPN provider and the LTE provider used IPv4 addresses only and therefore the clients couldn’t connect to the server.
The test connection from my internet access and my LTE network (both with IPv6 addresses) and the SSL test of ssllabs.com/ssltest showed successful connections.

So in case someone has a similar issue, that the connection to his server doesn’t succeed although all configurations seem fine, check and do the following:

  • check your internet access if it is using Dual Stack (DS ^1) or Dual Stack Lite (DS Lite ^2)
  • in case of DS Lite make sure your clients use an Internet connection which assigns an IPv6 address (check for example with https://www.whatismyip.com/) in order to perform reliable tests
  • if your mobile phone doesn’t get an IPv6 address in 3G/ 4G network, check the Internet if your provider put guides only how to enable IPv6 as well (APN settings)
  • check your website with an external services which supports both IPv4 and IPv6; for example the ssl test mentioned above
  • for internal IPv6 tests use the server’s fe80:: address

For the router you want to keep in mind and make sure the following:

  • on your router you better configure: “Unique Local Address (ULA) - only assigned when there is no internet connection”
  • at least with me there were connection issues with “always assign ULA”

With IPv6 “port forwarding” is different!

While with IPv4 you access the external IPv4 of the router with your client devices and the port forwarding directs you to the server behind that router.
With IPv6 you need to access the server’s IPv6 global scope address. The “port forwarding” configuration on the router only opens the router’s firewall to allow traffic over that port to the device/ server.

I hope this explains a little and helps.


^1 Dual Stack means you have both, a globally unique IPv6 and a globally unique IPv4 address. Your router is reachable via IPv4 and IPv6 address from the Internet.

^2 Dual Stack Lite means you get a shared external IPv4 address (NAT) and a gloablly unique IPv6 address. Your router is only reachable via the IPv6 address from the Internet. Pretty much the only reason why you get the IPv4 address is to be able to connect to services and websites which have IPv4 addresses only.