No video calls in Talk after Upgrade to Nextcloud 14

I am running a Nextcloud 13 installation with Talk on Ubuntu 16.04 LTS. Also, I have a TURN-Server installed for video conferencing within talk.

After Upgrading to Nextcloud 14 I had to upgrade to Talk 4 which I did. The app is running and chat functionality is available. However, no video calls are possible - users get a message that they are invited to the call but are not able to join.

I would be grateful for any advice, thanks in advance.


Problem solved - made a mistake in the configuration of TURN server.