TMobile is no longer dual stack (IPv4 and IPv6) and therefore I don't always have an IPv4 IP address. As a result, when connected via cellular, I can not resolve my dynu.com address, so web sites and apps can not use that name to resolve back to my router. Please help with resolving dynu.com address.

Our IP update protocol supports both IPv4 and IPv6 update. You can use the latest version of the IP update client to update both IPv4 and IPv6 addresses for your hostname. This way if TMobile uses IPv6, it will use the most current IPv6 address and allow you to connect to your apps.

https://downloads.dynu.com/Files/Dynu.IUC/Dynu.IUC.Setup.zip