Back when I was running a tractor trailer, I used Copilot Truck on my laptop and as long as the wired gps antenna worked the system was flawless. Often gave me load limit warnings in time to avoid an old bridge or whatever.
Assuming your Copilot is the same company, it does not require internet access, but would have an antenna plugged into whatever is driving the screen/computer. The internet would also require some way to reach the internet, most likely a wireless connection through your phone. Unless the monitor is also the same box that houses the computer (quite possibly is if it is a simple android system), trace the monitor cable backwards to find the computer and see what's plugged in. There would have to be a GPS antenna plugged in somewhere, either at the monitor or the computer if separate. My experience with copilot taught me their supplied entenna was the weakest part of the system. Replacement entennas are cheap, but you need to find one with the same cable adapters. Let us know how this all works out.