Connection drops after 1 minute on MG7700

Same issue for me in Glen Mills, PA 19342 except my Motorola MG7700 modem won't connect at all. It connects and then drops off within a minute after being rebooted and reconnecting to the XFinity network. Technician came out today, said his modem tested fine. He suggested I go to Best Buy to buy a new one. But the MG7700 is still listed as a compatible device on their website! Will try hard reset and updating modem firmware next. Pretty frustrating as I've had no issues for several years until a maintenance/upgrade was performed in my neighborhood this week.