DVR Play back has garbled video and choppy sound

 During a DVR playback the video skips, is garbled and the audio is skipping with the video. The video and audio is good when watching "live" tv, not recorded shows. If I try to fast forward the video freezes and it will take a while to move forward or reverse. This problem exists on any of the six boxes I have in the house. I've tried all of the troubleshooting techniques Xfinity has asked me to do,  but the issue is still there after months and months of frustrating problems. Sometime a message will appear on the screen "we are attempting to fix your playback issue".  It works for a moment but it always returns.

It also appears to be more severe when the weather is windy. My cable coming into my house has been checked by Xfinity and the main box has been replaced twice along with some of the  other boxes to try to correct the problem. All the ends of the cables have been replaced, cables inside the house have been replaced, the splitter amplifier has been replaced but the problem still exists. what's the point of a DVR if you can't watch what you record. I pay an awful lot of money every month not to be able to use all the services. I am furious that I can't sit down and watch a show when I want without a playback problem. FIX IT WHAT EVER IT IS WHERE EVER IT IS PLEASE.