[GTALUG] Network disabled on PC after last update

I have a desktop computer that dual boots into Ubuntu Studio and Windows 10. It is connected to the internet using a cat-5 cable to my router. After the last update and rebooting, it turns out that I no longer have ethernet on Linux. This is not true on Windows, as I am writing you this email from the same computer. I strongly suspect that there is an update issue that is disabling ethernet on Linux. Right now, my computer is in splendid isolation from the rest of the world. I can't even see computer resources from other computers in my apartment. I also can't see the router itself through my browser. Any ideas as to what to do next to diagnose the problem? Paul