Had this problem for a few months now and still cant solve it. I have submitted diagnostic logs as well a few times. On APPLE TV 4K, tuner sharing is enabled, Wifi is 150 up/150 down. Every morning between 10am and noon I'll have channels playing in the background and then it will just completely freeze and after 5 minutes of sitting idle, it will say "tuner not available". The log goes from "watching ---" to "Closed connection". Can't seem to figure out what causes this.
It looks like there's something wrong with your network setup.
I see logs of errors about DNS lookups failing, UPnP issues, and it appears that you may have two routers between you and the internet.
2020/06/26 16:12:55.613778 [ERR] Failed to refresh auth: Post "https://community.getchannels.com/dvr/api": dial tcp: lookup community.getchannels.com on 192.168.1.1:53: dial udp 192.168.1.1:53: connect: network is unreachable
Those issues appear to be what is causing you the problems.