You might need to use a process of elimination to figure out what (if any) other device in your HDMI chain is causing the issue. Such as unplugging other devices, connecting the ATV directly to the TV. Or disabling CEC on other devices. I had issues once with my Marantz Receiver when network control was enabled.

There were some bugs in certain earlier versions of Infuse that caused my metadata to clear. But I haven’t seen it occur for a long time. You’ll likely be fine.

Great setup, by the way. You won’t be disappointed.

The absolute best image quality (50-80+mbps) is going to come from having digital file copies of the 4K Bluray. Which you store on your local network and play back your AppleTV using apps such as Infuse. That requires ripping the discs yourself or aquiring them via questionable means. Otherwise streaming from AppleTV+ service with upwards of 30mbps.

Not quite what you’re looking for, but LG TVs have a feature called “enjoy TV sound together” for this exact purpose. You can output to multiple audio sources.

http://kr.eguide.lgappstv.com/manual/w22_mr2/global/Contents/settings/accessibility/simultaneousaudio_k_u_b_e_c_a_t_j/eng/w22__settings__accessibility__simultaneousaudio_k_u_b_e_c_a_t_j__eng.html

The Logitech doorbell used to have a lot of problems with overheating in warm weather and losing connection. They fixed it with a firmware update last year I think. Mine has been rock solid.

It’s use 125mpbs max for 4K Bluray. But typically between 50-80mbps. I

One reason could be that they have been mastered differently for streaming vs bluray.

The TrueHD audio is also lossless compression, while the DD+ version is compressed.

Is there a difference in sound when the file is in Dolby Digital Plus 7.1 vs. DD+ 5.1 ? vs. TrueHD 7.1?

Unfortunately the AppleTV only supports atmos when it’s in a Dolby Digital Plus 5.1 container. DD+ 7.1 or TrueHD is not supported and will be converted to multichannel PCM.

https://support.firecore.com/hc/en-us/articles/217735707-Audio-Options-tvOS-