Loose room access after some seconds

Hello all,

We have a self-hosted server and doing the first steps to configure Jitsi to our needs (doing also my first coding steps…).
We have already setup authentication and are able to access rooms per login/pw.
Most of the time it happens that we I can access the room and then this error message appears --> screenshot.

Do you have any idea why is that?
Thanks a lot for your help,

The js console logs will give more details what is the error.
It can be missing port forwarding, or some other misconfiguration