Recording of shows are freezing pixalating

my DVR is not recording the programs properly I get the recordings are freezing, pixelating black screen with white dots not fast forwarding this is on CBS, MSNBC, CNN messages from Xfinity to try again this had been going on for 10 days. I tried using my iPhone that's not using xfinity wifi and I'm.still getting same results 

Also test were ran and and all of the test state that everything is working we checked all of our cable wires and plugs and they are all functional