X1 Box frequently freezes or displays an error message when playing web based content and certain channels

For the last few months, my X1 box has been freezing, stuttering, or otherwise throwing an error code when attempting to play any web-based content (DVR, apps, etc) and even for certain channels like Disney Jr and Nick Jr. I've replaced the X1 box at the local Xfinity store with no success and installed an approve moca filter on the incoming line, again, with no improvement. I've also chatted/spoken with support...they did remote troubleshooting for 20 minutes and said the problem was resolved, but it is not. It seems like this has been happening since Xfinity sent a message saying that service in my area had been upgraded, so I'm unsure if its related to that. At the same time, internet speeds in the house have also seemed to become unstable, sometimes momentarily decreasing to ~10mbps and then returning to the normal speed after a few moments. Any idea why this would be happening...its becoming quite annoying.