Zerotier servers China

Thank you reply!

Yes I have access to the settings of the 5g modems (can connect to them via wlan from a pc).
One machine is a RPI 4 and the other one a pc on Win10.
The app I am running is UAWmatrix. I could try asking in their forums. Just started here since I think you may have a solution.
Anything in the settings you like me to check?