Router completely loses connection to the network every few minutes.

Ever since Xfinity did maintenance over a week ago on our network in Gardner, MA, my internet has been cutting in and out every few minutes. I check my network monitor in the Task Manager, and the ethernet connection literally just disappears for about 30 seconds at a time, going down to 0 Mbps (I'm on the gig plan). Only my desktop is connected to the network, so it's not a question of too many devices. I've restarted the router multiple times, power cycling it, and it still does it. I've tried a few other fixes like using another browser, or setting the live streams I watch to use only Ipv4 instead of Ipv6. It's particularly noticeable on the site Twitch, where when I watch live streams they will just stop and buffer for 20 or 30 seconds at a time before coming back. This was NOT happening prior to the maintenance.