Internal Server error only at the Talk App

Hey, I started a few days ago setting up my own server at home and tried to learn some stuff about linux. After that I installed Nextcloud. Everything worked fine.

I had only a few Problems with the app Talk (spreed).
Text Messages are working fine, but there was a Problem with the audio and video chat.
My internet should be good enough and the cpu of the server was never over 5%. The Ram was never higher then 40%. So in my understanding there is a software issue with my nextcloud configurations.

I tried to install my own TURN Server to make everything a little bit faster but I was not able to do that. I don’t know what the problem was. I just used explanations out of these forum.

The main problem is now, that I crashed something while installing Coturn (and I don’t know what).
The Talk App is still working with the iPhone app. But when I try to go to the web version of the talk app, I got this message:

Interner Serverfehler

Der Server konnte die Anfrage nicht fertig stellen.

Sollte dies erneut auftreten, senden Sie bitte die nachfolgenden technischen Einzelheiten an Ihren Server-Administrator.

Weitere Details können im Server-Protokoll gefunden werden.

Technische Details

  • Entfernte Adresse: 46.89.18.200
  • Anfragekennung: T3cF0tNh7BNdXbNnhetm

I tried to look into the log files, but my nextcloud log files are empty:
/var/www/html/nextcloud/data/nextcloud.log
/var/log/nextcloud.log

EDIT:

I found the following log file:

{“reqId”:“nKnfA7yUXi0UMGwAwa3w”,“level”:3,“time”:“2019-03-14T10:51:10+00:00”,“remoteAddr”:“XX.XX.XXX”,“user”:“XXXXX”,“app”:“index”,“method”:“GET”,“url”:“/index.php/apps/spreed/”,“message”:{“Exception”:“Error”,“Message”:“Minimum value must be less than or equal to the maximum value”,“Code”:0,“Trace”:[{“file”:“/var/www/html/nextcloud/apps/spreed/lib/Config.php”,“line”:157,“function”:“random_int”,“args”:[0,-1]},{“file”:"/va$

→ I reinstalled the talk app, no change

Als I tried:
-installing nextcloud again
-deinstall Coturn
-restart everything a couple of times
-wait 10 hours and tried again
-stoped fail2ban and tried again

I hope someone can help me.
Thanks a lot in advance!
Steve

I found these logs in my error.log file from apache2.
Maybe this can help.

[Thu Mar 14 09:34:56.419934 2019] [authz_core:error] [pid 2493] [client xxx:xxx] AH01630: client denied by server configuration: /var/www/html/nextcloud/config

[Thu Mar 14 09:35:28.216358 2019] [authz_core:error] [pid 2518] [client xxx:xxx] AH01630: client denied by server configuration: /var/www/html/nextcloud/config

[Thu Mar 14 09:36:00.174626 2019] [authz_core:error] [pid 2469] [client xxx:xxx] AH01630: client denied by server configuration: /var/www/html/nextcloud/config

[Thu Mar 14 09:36:32.225637 2019] [authz_core:error] [pid 2474] [client xxx:xxx] AH01630: client denied by server configuration: /var/www/html/nextcloud/config

[Thu Mar 14 09:37:04.176319 2019] [authz_core:error] [pid 2518] [client xxx:xxx] AH01630: client denied by server configuration: /var/www/html/nextcloud/config

[Thu Mar 14 09:37:36.215286 2019] [authz_core:error] [pid 2469] [client xxx:xxx] AH01630: client denied by server configuration: /var/www/html/nextcloud/config

[Thu Mar 14 09:38:08.189802 2019] [authz_core:error] [pid 2474] [client xxx:xxx] AH01630: client denied by server configuration: /var/www/html/nextcloud/config

[Thu Mar 14 09:38:40.209824 2019] [authz_core:error] [pid 2518] [client xxx:xxx] AH01630: client denied by server configuration: /var/www/html/nextcloud/config

[Thu Mar 14 09:39:12.177991 2019] [authz_core:error] [pid 2517] [client xxx:xxx] AH01630: client denied by server configuration: /var/www/html/nextcloud/config

[Thu Mar 14 09:39:15.175635 2019] [authz_core:error] [pid 2519] [client xxx:xxx] AH01630: client denied by server configuration: /var/www/html/nextcloud/config