Trying to use Dynamic DNS on Att Hotspot (Netgear LB2120) and seeing different IPs, how can I dial into this network from WAN?

I am trying to setup a external route into a network that is using ATT, a Netgear LB2120 sim modem/router (set to Bridge), and a TPLink router with Dynamic DNS and port forwarding so I can connect to a IP connected system.

The issue seems to be that the IP addresses I see are different at 3 levels and the Modem .
The TPLink router shows an IP 10.32.xx.x
The Dynamic DNS service reports 107.77.xx.x

The website WhatsMyIp shows my IP as 166.170.xx.x

I was reading about how there are not enough IPv4 so ATT uses a system that shows an IPv4 to outside world but internal routing is different. Getting a Static from ATT is cost prohibitive.

Anyway, can someone educate me a bit so I can ask the right questions?

My work around will be to put a Compute Stick behind the router so it can be remoted into. Not ideal.

Thanks!