Xfinity remote repeatedly loses connection with cable box

We recently upgraded our Cable service to have more channels. The new remote kept losing its pairing/connection with the new cable box. It would work for a day, then after turning off the TV overnight or for a while, upon turning it back on, the remote wouldn’t work - couldn’t adjust volume, change channels, see the guide, etc. I could re-connect the remote with the box only by removing the batteries from the remote, unplugging the cable box from power, then plugging the box in again, replacing the batteries and letting the box reboot. After a couple of weeks of this, I exchanged the box and remote at our local Xfinity store for new ones. But the same thing continued to happen. I then replaced the TV with a brand new one. Same problem. The. I replaced the HDMI cable. Same problem. We are not having any problems at all with the bigger TV, which is connected to the DVR. Help!