I'm having trouble getting UAVCast to work with a Huawei MS2372 modem. On the Cell Modem page I can't get the Green light to go on although I've tried a lot of different options on the page. Here's a link to the logfile: https://www.dropbox.com/s/y03spq11otox8ea/UAVcast-Pro-logfiles-randy-19Sep2019.zip?dl=0
To provide some background, I've setup UAVCast following the UAVCast wiki instructions. The RPI3 has a Huawei MS2372 modem plugged into one of it's USB ports. I've also connected a an ethernet cable to the RPI3 which allows me to connect to the UAVCast web page (i.e. URL=http://192.168.2.19/cell-modem).
The RPI is connected to a CubeBlack flight controller's Serial1 port. The flight controller is running "latest" ArduPilot (Copter-4.0.0-dev). I've got Mission Planner running on my main PC and it's successfully connecting using UDP (over the LAN). I can move the flight controller around and see it's attitude in Mission Planner update.
BTW, I'm one of the main developers of ArduPilot so I'm happy to dig into the ardupilot parts but I honestly don't know a lot about Ubuntu and networking.