Internet drops dozens of times per day even after tech visit

Hello, I just activated xfinity service at my apartment and everything went fine for the first few days until I started getting intermittent connectivity drops. My modem is a Netgear CM1200 and I'm hardwired through a switch to my PC. I've tried rebooting the router probably 20 times as well as a couple of hard resets and I still can't maintain a stable connection for more than 30 minutes or so. Every device connected to the modem drops connection when this happens and it can be out anywhere from 5 minutes to 30 minutes. I called comcast and had a tech come out to look and he redid the line coming into my apartment but said he couldn't find the "main line" and it may be running through one of the other apartments in the building. Everything seemed fine when he left but of course it started dropping again within an hour or so. I took screenshots of my downstream and upstream stats and pasted them here: https://imgur.com/a/6afrYRl Is there anything else I can do on my side or am I going to have to keep calling and get another tech out here? Any help you guys could provide would be fantastic