i have checked the DNS settings. I have even changed them. The problem still exists.
I have had the same configuration of my network for years. I put all the apple TV's and hubs and IOT devices on a network that only has access to apples IP space and the ability to resolve via my internal DNS server.
Over time this is what i have noticed.
With each upgrade apple tries to force the hubs and TVs to be on the same VLAN and SSID as the cell phones. I have always used MDNS and mac address blocking on the cell phone network to force the TVs and hubs to be on their own restricted network. For years i have had no issue with this configuration but with each iteration of upgrades there are more and more issues that pop up.
This latest issue of the apple tv network being unavailable is a new problem. Since no other apps and no other devices have any issues i have to rule out all internal settings and confirm that this is an apple issue.
The solution for me so far is to just reboot the apple tv. Once rebooted everything works again. If it was my internal network it would not work even after a reboot.
I don't expect any support from apple. they have never responded to anything. any and all tickets i have opened in the past never make it to any resolution.
I hate to say it but i think youre all on your own to figure out what the issue is.
For all the people that have a flat network. Meaning one VLAN and one SSID. The default settings of all SOHO WiFi routers are to allow everything out. DNS is external to your network so unless you have modified the internet router the problem is with apple. if this is your setup. i would suggest factory reset your WiFi router and reboot the Apple TV and see if that fixes it.