Clients can't connect 403

Hi,

I am debuging a NC installation (23.0.0.) of my friend. It’s running on debian bullseye / Apache 2.4 /php 7,4.

The webinterface is working well. I can mount the space using mount.davfs.

However, I can’t connect with any client - my friend reported his Windows client won’t connect and I tried 2.6.2-1build1 on ubuntu and 3.18.1 on android Apache error log:

[authz_core:error]  AH01630: client denied by server configuration: /var/www/html/nextcloud/status.php
[autoindex:error]  AH01276: Cannot serve directory /var/www/html/nextcloud: No matching DirectoryIndex (none) found, and server-generated directory index forbidden by Options directive
[authz_core:error] AH01630: client denied by server configuration: /var/www/html/nextcloud/status.php

Apache Config:

<VirtualHost *:443>
DocumentRoot "/var/www/html/"

<FilesMatch \.php$>
       SetHandler "proxy:fcgi://127.0.0.1:9000"
</FilesMatch>


<IfModule mod_headers.c>
      Header always set Strict-Transport-Security "max-age=15552000; includeSubDomains; strict-origin; preload"
      Redirect 301 /.well-known/carddav /nextcloud/remote.php/dav
      Redirect 301 /.well-known/caldav /nextcloud/remote.php/dav
      Redirect 301 /.well-known/webfinger /nextcloud/index.php/.well-known/webfinger
      Redirect 301 /.well-known/nodeinfo /nextcloud/index.php/.well-known/nodeinfo
</IfModule>

<IfModule dir_module>
DirectoryIndex index.html index.php
</IfModule>

ServerName FQDN
<Directory "/var/www/html/">
Options MultiViews FollowSymlinks
AllowOverride All
#Order allow,deny
Require all granted
</Directory>

TransferLog /var/log/apache2/nextcloud_access.log
ErrorLog /var/log/apache2/nextcloud_error.log

SSLCertificateFile /etc/letsencrypt/live/FQDN/fullchain.pem
SSLCertificateKeyFile /etc/letsencrypt/live/FQDN/privkey.pem
Include /etc/letsencrypt/options-ssl-apache.conf
</VirtualHost>

nextcloud config:

<?php
$CONFIG = array (
  'trusted_domains' => 
  array (
    0 => 'FQDN',
  ),
  'datadirectory' => '/var/local/data',
  'dbtype' => 'mysql',
  'version' => '23.0.0.10',
  'overwrite.cli.url' => 'https://FQDN/nextcloud',
  'htaccess.RewriteBase' => '/nextcloud',
  'overwritewebroot' => '/nextcloud',
  'overwriteprotocol' => 'https',
  
  'default_language' => 'de',
  'default_locale' => 'de_DE',
  'default_phone_region' => 'DE',
  'dbname' => 'nextcloud',
  'dbhost' => 'localhost',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'dbuser' => 'nextcloud',
  'dbpassword' => '***',
  'installed' => true,
  'log_type' => 'file',
  'logfile' => '/var/local/data/nextcloud.log',
  'logfilemode' => 416,
  'loglevel' => 2,
  'logdateformat' => 'F d, Y H:i:s',
  'maintenance' => false,
  'theme' => '',
  'app_install_overwrite' => 
  array (
    0 => 'calendar',
    1 => 'pdfdraw',
  ),
  'mysql.utf8mb4' => true,
  'mail_smtpmode' => 'smtp',
  'mail_sendmailmode' => 'smtp',
  'instanceid' => 'ocvgulqk3mdq',
  'memcache.local' => '\\OC\\Memcache\\APCu',
  'updater.release.channel' => 'stable',
  'mail_smtpsecure' => 'ssl',
  'mail_smtpauthtype' => 'PLAIN',
);

I already tried a chown -R www-data:www-data on the nextcloud directory, but no luck :(. Any idea why the client can’t connect to resources that are usable by a browser without any issues? TIA.