Problems with Jitsi-Meet Android App

Hello everyone,
unfortunately, cell phone clients using the jitsi-meed Android App do not work with my Jitsi server installation. You can log into a conference, but audio and video are not transmitted. The mobile phone participants are always displayed as muted. With Windows participants, everything works perfectly. They also do work perfectly when I’m using meet.jit.si. It is also working when I use a browser with the mobile phone.
Any idea what’s the difference between the app and the browser?

What is the version of your Jitsi server and your app?