Jitsi's running halfway and then disconnecting all the time

Good evening,

Being very original I installed jitsi on my nginx server which runs thanks to ubuntu-server 18.04.4 LTS. I followed to get the tutorial : https://www.linuxtricks.fr/wiki/debian-installer-son-serveur-de-visioconference-jitsi-meet

But when I connect to a local network, jitsi works on the other hand several features don’t work: I can’t set a password (the option doesn’t appear), the “stop meeting” button doesn’t work, and moreover it disconnects/reconnects regularly. At first I thought it was the browser (firefox) but I have the same problem on all the others…

I then tried to install it on my linux laptop with the same procedure, and there miracle all works… Yet I have the same version of ubuntu (but not the same kernel).

Does anyone have an idea of the cause of my problem? I forced the use of JDK8 but it doesn’t change anything.