WIZnet

Your drone is online.
Why can’t you reach it?

That is the real BVLOS telemetry problem here.

Pixhawk sends MAVLink over UART.
LTE / satellite backhaul may put the airborne side behind CGNAT.
The ground station cannot always start the session first.

One concept:

Pixhawk UART → WIZ-IP20 → LTE / satellite IP backhaul

Links are in the first comment.

How would you solve it — TCP client, UDP hole punching, VPN, or broker relay?