Jitsi meet not working on Apple devices or Firefox

I can not make a video or audio connection either using Firefox on MacOS or Windows or Jitsi Meet on iPhone or iPad. The connection seems to be established but no video or audio is transferred. In the server syslog file I see error messages like

Apr 20 18:57:57 jitsi turnserver: 6402: session 003000000000000026: TLS/TCP socket closed remotely

Only Google Chrome seems to establish a working connection