Device having difficulty connecting to internet. Every single day!

So the high definition dvr/cable device has difficulty connecting to the internet, although we have an excellent connection to the internet on all other devices. Yes, replaced the cable modem/router with a new one that is Comcast compliant. Still same problem. Comcast ran a new cable from the pole top to our home a couple of years ago, which solved a lot of problems. Just two tv’s and the internet connection. Not a lot of devices online. Only the tv signal has problems with the internet. I’m beginning to suspect it is the high definition dvr/cable box that is the problem, because it usually requires resetting or unplugging it (it locks up such that it cannot be switched off with the remote) from power. Good grief!!!