I've been having intermittent problems with my X1 service, internet (wired & WiFi) and phone for years. We have called & chatted numerous times over the past several months, with no solution. We recently upgraded our internet service and replaced the modem, same problems. I've replaced coax and Cat-5/6 cables, rebooted, power cycled, reseated, tightened, re-tighten, refreshed, reset, .... No help from Comcast/Xfinity support. I had a chat session with a nice lady in The Philippines and courteous gentleman in India, and neither could fond a solution. I was told I would get a text or call from "Comcast Advanced Support", it's been a week or so, no call or text, no resolution. I loose my phone and internet service several times a day, the TV frequently freezes, and the remote control clicks return a RDK-03033 error or similar code, unable to connect to the internet.
Additional notes: A few days ago, my wife was on the phone with Comcast/Xfinity support. The person on the other side of the call was testing rebooting our system for about 30 minutes and "found a problem and fixed it". Needless to say, not fixed. I've dropped and regained my internet and WiFi twice in the last hour. No DNS service, unable to connect to the internet, again.