I am experiencing the same problem. Tech came out and replaced the DVR box, but this resulted in no change. Additional information: When I stream Netflix on a non-DVR Comcast box, the DVR box exhibits the stuttering effect on recordings and Live TV. So it appears that just by having the Netflix stream on the cable network connection within the house affects the X1 DVR box. Perhaps the DVR is reacting to what it sees as some type of sync or command pulse in the Netflix stream.
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