I just had this issue after upgrading my Xfinity service. After 3 visits it was finally determined that the signal booster the 1st technician installed was causing the noise on the line and thus the pixelation. Once that was removed from equation, everything is fine. They arent even sure why he installed it in the 1st place. This is the 2nd time they have completely rewired a house only to find out it was the signal booster. Hope this helps you out.
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