So.. following the problem with many #Jitsi instances that are not working well with more than two people, I've rebuild my implementations from scratch, allocated more resources and it should handle 15+ participants per room by now. Sorry for the downtime the last days. Not I guess we have one more working properly.
Feel free to test and give feedback.
For people who care about, support, or build Free, Libre, and Open Source Software (FLOSS).