Just sharing a permanent fix for AppleTV Dual HomePod connection consistency over WiFi...
Hello,
I've searched our forums and researched the above issue online but didn't find an absolute straight answer to resolve constant connection drops between AppleTV and HomePod Stereo setups that I was experiencing for several months until I solved the issue myself; so I decided to share with the community in hopes that it will improve quality of life and offer some relief to anyone dealing with this at the time of this writing.
The fix is simple: Log-In to your WiFi router's home page and go to Wireless settings option, then manually set any identical channel bandwidth MHz settings to match each other. In my case I set 5GHz-1 & 5GHz-2 to 80MHz, but doesn't really matter what you've chosen on your end as long as they both match (see attached screenshot for visual clarification).
P.S.: I've noticed periodically that AppleTV will disconnect from HomePods when powered off/on but when you go into its video and audio settings you'll notice it will still see your HomePods on your network and all you have to do is select them for a stable reconnection. This behavior is no fault to your network router nor HomePods it's just a fact that the AppleTV-HD (unsure about 4k) doesn't auto reconnect them but this happens rarely after the aforementioned fix so perhaps it's because of background maintenance routines or system TVos updates.
Apple TV HD, tvOS 17