Channels on Apple TV can't find HDHomerun

I have an HDhomerun connected directly to my ATT gateway with Channels app installed on 2 separate Apple TVs. It's worked great for a year now. All of a sudden, one of my Channels/AppleTV setups can't find the source HDhomerun..the other works fine. I've even tried typing in the IP address of the HDhomerun and it comes back with an error.
any debug i can try?

Are you able to access that IP from another phone? Have you tried the Channels app on iphone or ipad?

What is the IP assigned to the HDHR and the IP assigned to each ATV? Are they in the same subnet?

checked my router and confirmed the ATV and HDHM are on the same subnet. 192.168.1.153 for ATV, 192.168.1.150 for HDHM. I event tried renewing the DHCP lease. pinged from my laptop and got responses from both.

Quite strange. Is the ATV on Wi-Fi? Is it connected to a guest network maybe?

Maybe you can swap the two ATVs and see if that changes anything.

Yes, the ATV is on Wifi and I don't have a guest network setup. I even tried resetting the DHCP address range and renewing the IPs. both the HDHM and ATV got new IPs...still didn't work.
I'll try your advice and swap the ATVs to see if the issue travels.

You said the HDHR got a NEW IP from DHCP. Maybe my superstition but I always assign a Static IP (in the DHCP Server on the router) to my HDHR Devices and also the Device the DVR is running on (and others) so that they never change. Maybe because I heard years ago that an active device may not check again for the New IP of a Host Machine on the network that quickly. I also pick IP's above .200 for my Static devices.