User couldn't authenticate as host

Hi there,

I run my own jitsi meet instance which is secured by the build in authentication. This is working fine so far, so not everybody is able to open new rooms.

But one of the users has a very strange behavior. He is unable to authenticate himself as a host because he can’t click the “I’m the host”-Button.
The problem occured in chrome as well as in firefox.
I checked the network tab and the console tab of both browsers but there are no resources missing or specific js errors. The jitsi meet app is working fine from the same wireless network.

Any ideas what I can do to find the issue - currently I have absolutely no clue.