DirecTV different on two identical HR20-700's

Have you tried a full cold restart of the one with the problem? It sounds like an issue specific to that device. Given you have a working device, you might want to compare settings on the two as well. Turning off power on a DirecTV receiver is not the same as restarting it.

Thanks for the amazingly quick response!!!

I did unplug the errant DVR and waited 45 seconds before plugging it back in. I then waited the requisite 10 minutes while it went through the entire reboot process.

What settings might be different on an HR20-700? I ask because I can’t think of any.

I found the settings that are in question in Settings/Whole-Home/External Device.