When using cellular data can't ping or connect from Galaxy s21 ultra phone to Windows machine

I’m using zerotier to remotely connect to a surveillance camera server. If my galaxy 21 ultra (running Android 12) is connected to a WiFi network everything works. But as soon as I switch to cellular data I can’t ping or connect.

The strange thing is that with my older Galaxy s9 I have no problem connecting to my camera server over LTE with all the same settings.

Another very strange thing is that when I first set up and authorize the S21 to access my zerotier network and ping/connect etc it works but then when I switch back to Wi-Fi I can’t connect via LTE again after that.

I have the “use cellular data” box checked.

Any help with this would be much appreciated.