Can't ping ipad when switching from wifi and LTE

If I start Zero Tier on wifi with my ipad I can ping it from my mac which is on wifi.

If I switch from wifi to LTE, I can’t ping.

If I reboot my Mac, start Zero Tier on my iPad on LTE, then start zero tier on my Mac I can ping my iPad from my Mac some of the time

Is there an issue switched from Wifi to LTE? My ipad settings allow cellular data when using Zerotier