Live TV stuttering/freezing since DVR upgrade

I was instructed via an Xfinitymessage on my TV that my DVR needed to be exchanged for an upgraded one. I followed the instructions and installed my DVR. Since then my live TV will freeze and stutter (it will repeat the last 1/2 second repeatedly). After a minute of this it will recycle on it's own. It will repeat this cycle about 10 times or so. We did not have this problem with the old DVR. Apps are working  fine. We checked the connections and they are tight with no corrosion. Our other TV which doesn't have a DVR but has the Xfinity adaptor is not having any issues. We have unplugged the DVR in the hopes it is some kind of buffering issue but no luck. We visited the Xfinity store and received a new DVR. It appears refurbished as the batteries were dead in the remote and it did not have an HDMI cable.  We installed it and the same problem still exists. We had a tech about a year ago measure our signal and he said it was good. So...we pay $220 a month for internet and the middle TV plan but aren't enjoying the benefits of the service. We will give Xfinity about one more month to resolve this or we will be forced to use YouTube TV or something similar. Once again this issue started with the upgraded DVR.