This problem started on my setup a few months ago, a setup that hasn't changed for many months. I have Samsung UHD. I can't say what the Xfinity box is without checking. I have tested and tested and have come to the conclusion that if I turn the power off via the Xfinity remote too soon after doing anything else with the remote, such as change a channel or return from On Demand after watching a show, or return from smart mode on the TV, back to the Xfinity box and immediately turn off via the remote, the next time I want to turn on to watch, the Xfinity box is MIA. This started about the same time as it started not returning to where I left off watching an on demand show if I returned to it later to resume. Sometimes it returns to as much as a couple minutes back from where I left off. I have proven to myself that if I change channel on Xfinity, return from On Demand, or return to Xfinity from my smart TV, as long as I give it a few minutes on one channel before hitting power off with the Xfinity remote, it will work fine in the morning.
Do not tell me this is my TV's fault, or an HDMI cable. This exact issue started on the very same day with a neighbor who has a Sony smart TV. As a computer guy, I'm pretty sure this is some sort of memory issue with the Xfinity box where it can't remember where it was or what it was doing or know that it should be looking for a "handshake", if it was very recently asked to do something before the power off was requested by the remote.
When the Xfinity box is MIA, I just turn it off and on with the front power button. In a couple minutes, it shows that it's alive, and then starts working.
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