I don’t remember my exact setup, but from my troubleshooting I think this will help some users.
Setup is: Samsung A95 TV, AppleTV 4K, Arc, Sub mini, 2x One SL (rear).
I had problems with 5.1 sound from Netflix, HBO, etc. when the soundtrack was 5.1. Strangely enough when sound was Atmos everything worked fine.
I have done much of the troubleshooting tips, removing surround speakers, disconnect Arc, reset system (speakers), reconnect everything. Configure ntwork. Reset settings on TV. Reconnecting everything in a specific order, new HDMI cables. The lot.
In the end, my solution was simple.
Make sure your TV is set to eArc and PassThru for the HDMI to Arc - This is the correct setting.
On the AppleTV:
When watching something with 5.1 sound:
Settings → Video and Sound → Format: Set this to Dolby Digital 5.1
When watching something with Atmos:
Settings → Video and Sound → Format: Set to Atmos
(I have norwegian language, so path might not be correct!)
This will hopefully remove the stuttering/choppy sound from your rear speakers. (Since for some reason, when AppleTV is set to Atmos the passthru for 5.1 sound is broken somewhere on the way to your One’s).
Do remember to set it Atmos when watching something with Atmos sound. You can hear the difference. (At least I tell myself that I can 😊)