Hi Luca,
Concerning yesterday's JITSI issue I would like to report a few items to help you diagnose :
1. Concerning your channel it was my first attempt to get in touch with Wikifunctions
2. I do use video conferencing with other groups in wikimedia without problems, eg wikibase, wikidata, or my local chapter in Belgium (using the same infrastructure)
3. However I feel a little guilty, I do know why ? the Jitsi Chrome extension was not activated during my trial and the software invited me to install a Jaas server. What I did blind !
4. Anyway after having activated the chrome extension, I was able to see your face, echo myself, close the camera and microphone and browse all the options. But having no sound.
5 I had the impression to be the sole participant awaiting the session to start.
6. I did not check my inbox to start an alternative call.
7. That's all. I will try again next time.
Dominique