Ground unit to use onboard LTE

Hello, i have a modem on the network on the drone, would it be possible to have the ground unit to use the modem as a gateway for internet? Basicly i need the ground unit to use modem onboard as a gateway.

What i would need is that all the traffic that is not or would be routed to that is my modem router.
In this way i would have internet on the pc i connect to the ground station hot spot and the groundstation itself would hav internet for maps and for a special app we use that needs the internet.

So far i added some routing to the pc attached to the hotspot and to the onboard router and the 2 networks (144 & 43) can see each other but to reach outside i would need to tell to reach gateway for internet.

At the moment as a workaround i made an hotspot with a raspberry and attached it to the micro usb with an ethernet adapter, than i log to the raspberry wifi with my controller and internet requests are routed to the onboard lte router trough ethernet bridge. I can connect with my laptop to the new raspberry hotspot too and reach 144 onboard network as well as having internet trough the onboard router.
Obviously if the ground controller itself could route internet traffic of itself and 43 wifi network directly to the onboard router would be much better.