What type of hardware are you using: VPS bought online What YunoHost version are you running: 12.0.16 How are you able to access your server: The webadmin
Describe your issue
Jitsi video bridge is broke when 3 or more people join no sound or video
If you are writing this about Jitsi, you are welcome to explore alternatives and check their own support.
If you are writing this about YunoHost, well, consider this your first and final warning. This is not welcome here.
Is your Diagnosis in the YunoHost admin complaining about anything related to Jitsi, firewall, services?