I've been trying the firewall check and it keeps failing. If I do online portscans it shows the port is open. Only stun servers are ok the others all show not reachable. How to further diagnose this? I can also receive calls so it just seems the firewall check is wrong somehow. Tried using the app through 4G so it uses the tunnel whitch also failes in the firewall check. How does this check verify the connectivity? I'm using latest 3cx debian iso also made sure all updates are installed.