Does ZT have any tools that would run on a Raspberry Pi to diagnose why the ZT connection with T-Mobile 5G Home Internet just dies occasionally? I would like to load some kind of an uptime monitor on my RPi to document uptimes and possibly diagnose communication issues. When I ran this exact setup on AT&T 4G WIFI, it was always up but now that I’ve switched to T-Mobile to get uncapped internet, it is only up about 85% of the time. It comes and goes like an ocean wave and T-Mobile certainly doesn’t have enough tech support to even discuss this issue. When I’m actually at the remote site, the internet seems 100% stable and fast (amazingly so). It only gets flakey when I connect via ZT.
Unfortunately it seems T-Mobile blocks a lot of UDP traffic, and ZeroTier is a UDP based protocol. A quick google search shows lots of issues with UDP over T-Mobile networks, and not just with ZeroTier. We’ve had some reports that it works OK if there is IPv6 connectivity end-to-end, but if the traffic is going via IPv4, then the UDP packets are blocked.
Thanks Grant. I’ll check all the settings end to end to make sure I’ve got 6 turned on. I believe I once turned off IPv6 because somebody told me it was the cause of my issues but I’ll turn everything back on and give it a try.
Very frustrating because TMO 5G is VERY fast (600 down and 60 up) and uncapped but apparently not compatible with ZT. So close and yet so far. 
Bob