Support intro
Sorry to hear you’re facing problems 
help.nextcloud.com is for home/non-enterprise users. If you’re running a business, paid support can be accessed via portal.nextcloud.com where we can ensure your business keeps running smoothly.
In order to help you as quickly as possible, before clicking Create Topic please provide as much of the below as you can. Feel free to use a pastebin service for logs, otherwise either indent short log examples with four spaces:
example
Or for longer, use three backticks above and below the code snippet:
longer
example
here
Some or all of the below information will be requested if it isn’t supplied; for fastest response please provide as much as you can 
Nextcloud version (eg, 20.0.5): 19.0.9
Operating system and version (eg, Ubuntu 20.04): Ubuntu 20.04
Apache or nginx version (eg, Apache 2.4.25): replace me
PHP version (eg, 7.4): 7.4.3
The issue you are facing:
Is this the first time you’ve seen this error? (Y/N): No
Randomly the nextcloud server send TCP RST packets only to clients outside of the firewall so it would appear that the server is offline but internally it is up and running fine. At some point it stops and the outside clients can connect fine
The output of your Nextcloud log in Admin > Logging:
PASTE HERE
The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):
<?php
$CONFIG = array (
'instanceid' => 'oc26q38iojq4',
'passwordsalt' => '***',
'trusted_domains' =>
array (
0 => 'nextcloud.***.com',
),
'datadirectory' => '/var/www/nextcloud-data',
'dbtype' => 'mysql',
'version' => '19.0.9.1',
'overwrite.cli.url' => 'https://nextcloud.***.com',
'dbname' => 'nextcloud',
'dbhost' => 'localhost',
'dbport' => '',
'dbtableprefix' => 'oc_',
'mysql.utf8mb4' => true,
'dbuser' => 'nextclouduser',
'dbpassword' => '***',
'installed' => true,
'mail_from_address' => '***cloud',
'mail_smtpmode' => 'smtp',
'mail_sendmailmode' => 'smtp',
'mail_domain' => '***.com',
'mail_smtphost' => '***.***.com',
'mail_smtpport' => '25',
'memcache.distributed' => '\\OC\\Memcache\\Redis',
'memcache.local' => '\\OC\\Memcache\\Redis',
'memcache.locking' => '\\OC\\Memcache\\Redis',
'redis' =>
array (
'host' => 'localhost',
'port' => 6379,
),
'maintenance' => false,
'updater.release.channel' => 'stable',
'theme' => '',
'loglevel' => 2,
);
The output of your Apache/nginx/system log in /var/log/____:
PASTE HERE