X1 pixelation in HD only

Hi there, @user_gq8sjg! Thanks for reaching out about the HD channels being pixelated but the others working fine. There may be a signal problem causing this. The SD channels do not need as much bandwidth and the 4K channels are internet channels (IP) is why you may only see that on the HD stations. I appreciate all the information that you provided about your setup, what steps you took, and testing between the channels.

Have you also tried a system refresh signal? You can send that by pressing the "A" button on the voice remote and going to the right so you can select the tile or by saying "system refresh" to the voice remote. 

If the issue is still present after you completed a system refresh, please send us a direct message with your full name and complete service address to “Xfinity Support”. That will allow us to the check the signals to your home and equipment. To do so, click on the direct messaging icon located at the top right of this forums page.

Here's the detailed steps to direct message us:
How to Send Us a Direct Message:
1.  Click "Sign In" if necessary.
2.  Click the "Direct Messaging" icon.
3.  Click the "Start new conversation" (pencil and paper) icon. 
4.  In the "To:" line, type "Xfinity Support".
5.  As you type, a drop-down list will appear. Select "Xfinity Support" from that list.
6.  An "Xfinity Support" graphic will replace the "To:" line.
7.  Type your message in the text area near the bottom of the window.
8.  Press Enter to send it.