OpenVPN or Dynamic DNS through Carrier Grade NAT?

Issue:Unable to setup a VPN Tunnel or Dynamic DNS when router is using a 4g Sim

Setup:

LoRa® Server:

Details: Hi All

I was wondering if anyone has any experience getting the VPN or Dynamic DNS working while using a 4g Sim which is using Carrier Grade NAT

I have attempted both and they both basically give me the error unable to resolve host/IP.

Has anyone got this working?