Since it's not your internet service, nor your home, you're going to be limited on how much you can experiment. I would start with just plugging a laptop into the router LAN port and using it that way ...
When figuring out what's happening with an errant internet connection, most folks turn to online or app-based speed tests, most notably the venerable gold standard, Speedtest.net by Ookla, for initial ...
Running speed tests didn't reveal anything, and latency looked perfectly fine, too. But it was doing ping tests and ...