Arc stays muted after 5 minutes

That’s definitely odd, I don’t have this issue on either of my Arcs, both of which are ‘controlled’ by my Apple TV remotes. I think I would call Sonos Support to discuss it.

When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

You might also make sure the ATV remotes are fully charged and/or updating the ATV OS.

If referring to your TV remote(s) try changing batteries. 

Also, check the HDMI connections on both ends.

​@ovrdrvn 

I had this before with my Arc, connected to my Samsung TV via eARC. Turned out I needed to turn off the Apple TV and Samsung, then hold down the power on my Samsung TV remote until it came back on with the logo (e.g. soft reset it), which seemed to reconnect the Arc properly.

Then turned the Apple TV back on, and I was able to mute and unmute freely with the Apple remote again. 

(Also, if this isn’t the issue your side, try pressing volume up a few times instead of the mute button on the Apple remote.)

Thanks. I tried resetting everything and also plenty of times. I’ve hit volume up or volume down. This only seems to be an issue on muting after the TV has set idle for approximately five minutes. It’s as if it goes into some sleep mode. Sonos suggested making a change in the Apple TV settings from auto to TV with IR. I’m experimenting with one set today to see if this works. 

​@ovrdrvn 

In my Apple TV remote settings for Volume Control, it shows as “Apple Remote via IR”, if that helps (which must have been via “Learn New Device...”).

That ‘soft reset’ I usually recommend as a ‘hard reset’ by literally unplugging the TV from the wall for two minutes. It may be CEC handshake issues you’re experiencing, too, so not only that reset, but checking the TV for updates from the manufacturer might help. 
 

In neither case (LG and Samsung) have I needed to switch my Arcs or Apple TV remotes over to IR. 

And switching ruined my iPhone being able to control it and ended up not working. That they send the amateurs in to give advice and waste consumers time is absurd. 

You are the one that chose to post to the community forum where users respond to other users.

If you want official Sonos support you need to contact Sonos Support instead.