Home Theater Questions? Ask a Technician for Answers ASAP
Hi, I'm Nathan.Sorry to hear that you're having trouble, but I'll do my best to help you. Please give me a few moments to review your details here.
Have you updated your cabling? One possible cause of this is that you do need a 2.0 rated (4k capable) high speed hdmi cable between each device, if you don't have that between the denon and the tv, it can cause this issue.
Having the hdcp upgrade would be helpful as well.
A few other considerations are the connections, make sure you are using the monitor 1/arc port OUT of the denon to the tv.
If that still doesn't help, let me know and there are some reset processes we can try to reestablish communication.
If you've checked all of these, then the issue is the board.
While the denon is capable of passing 4k video, that is only for unprotected 4k video. Your dtv box is most likely restricting everything with hdcp however, and in that case the ONLY option for this is sending the denon in to have the hdmi board upgraded (it is free) to support hdcp 2.2.
In the meantime, you can go direct to the tv with the hdmi cable from the dtv box, then run the arc or optical connection back to the denon for sound.