Try toggling the Match Frame Rate setting on the Apple TV. If it is currently set to ON, turn it OFF. If it is OFF, turn it ON. If this doesn’t make a difference, I would consider using a different streaming device like a Roku Ultra or Nvidia Shield rather than the Apple TV. The Apple TV seems to be the root of a lot of problems for many users, especially users with Samsung TVs.

Try a different sort of reset. Power down and disconnect HDMI cables from the whole crew. Wait at least two minutes because SAMSUNG TV’s don’t immediately trigger a reboot on power down. After the wait, power up the TV and ARC, then connect the HDMI cable. I expect that they’ll recognize each other. Now power up and connect the AppleTV.

As a test, force AppleTV and the SAMSUNG to deliver only PCM Stereo.

I suspect that there is an EDID (Extended Display Identification Data) spat. These are difficult to diagnose without specialized equipment. While you have no choice but to use the TV’s ARC port for ARC, try using another TV input for the AppleTV.

There are little “boxes” that can repair EDID and CEC issues, but it would be pure speculation on my part if I recommended one.

If you use the optical to HDMI dongle for ARC, is there any improvement?

If I would guess about the responsible party, I’d blame the TV, but I don’t have high confidence in this guess. EDID is sensitive to voltage levels in the HDMI ports. If the voltage drops a bit, the ports will  attempt to discover and renegotiate the shared, supported audio and video formats, One reason I’m not confident about this is because the picture usually drops out too while EDID is negotiating.

I’m thinking it’s a Samsung issue. I know many have had issues with the no sound with an Arc and Samsung . I also had that issue but had a Sony tv. Turns out it was the Sony software which the updated and issue resolved. But I thought it was the Arc…wrong.

It’s easiest to blame the last device in the chain, even if it’s relatively ‘dumb’. The problem will always be sometimes you’re right, sometimes you’re not, and as soon as you start talking about networks (CEC), things get complicated fast. 

It’s possible, although I consider it extremely unlikely, that the problem is the Sonos. I certainly agree with others that the problem may lie elsewhere, but it will be a process of elimination to determine where exactly it is. 

I would switch off HDMI-CEC on the Apple TV and any other connected device (obviously that excludes the Arc) and see if that sorts things… with Apple TV, I find the device has to be rebooted to properly disable its CEC feature… it doesn’t like to let go of control.

Thank you all for your comments! I too suspect it is the Samsung TV, but they have been the least helpful of  pretty much any support I’ve had the displeasure of interacting with recently.

For the record, this forum and working with Sonos directly has been a good (if unfruitful) experience and I do appreciate that.

Will do some of these things and report back.

Thank you. I tried this and it did not make a difference.

Thanks for your feedback.

I’d buy damn near anything to fix this. lol With a $2000+ TV I’d think I wouldn’t have to, but I’m sick of this. Heck, I’m ready to chuck the dang TV at this point. Ok, maybe not quite there yet.

I tried this reset and upon starting the first TV show on Hulu (a Bob’s Burger episode) I had no audio.

I moved the Apple TV HDMI cable from input 1 to input 2 on the TV.

I went back to the Apple TV settings and forced stereo.

Went back to Hulu and immediately had audio. In my short series of tests with this configuration I could not get audio to fail. Audio and video playback was also immediate. When I do not have stereo forced, there is always this delay where the video starts and the audio picks up a few seconds later - usually accompanied with the audio adjustment UI overlay showing up on the TV too (with what appears to be to automatic “volume up” presses. With forced stereo from the Apple TV this audio overlay didn’t show and audio started immediately.

I switched it back to “not forced stereo”, back to Hulu, and no audio.

I tried a few other apps with the “default” audio config and it seems solid. Even going back to Hulu and that same Bob’s episode the “multi-channel” audio stream plays.

I don’t really expect this to stay the case, but I will leave it this way and keep doing my daily watching to see if it fails again.

Edit: Exited Hulu, left the room for a bit, came back (all components still powered on), selected Hulu and no audio on the same episode of Bob’s from before.

I tend to think this too, but talking to someone there that could potentially help (i.e., not reading off a strict support script), seems hopeless. I keep waiting for a firmware update to fix it, but it’s been a year and it just went off support to make matters even more interesting. ;) 

Thanks. That’s good to know! I did turn this off a while back and never turned it back on. Today, when doing another reset I killed power to the entire home theatre end of the room (power move ;)) so the Apple TV got another complete power down (though it has gotten some over time too while I’ve been doing this troubleshooting).

Based on my replies to your kind feedback above, does it make sense something like this might resolve my audio issues? 

U9 ViewHD HDMI 2.0b 4K Switch 18Gbps 4:4:4 with Built-in HDMI to HDMI Audio Extractor Atmos Dedicated for eARC HDMI Soundbar / Receiver / TV Application | UHDe4x1

https://smile.amazon.com/dp/B097NXXDG6

At less than $200 less than the Arcana Fury, I’m willing to try it.

Try this link..might have info you need ..

https://en.community.sonos.com/home-theater-228993/arc-tv-sound-cuts-in-and-out-6842963

@Dogdad

Wow! Apparently this has been super widespread and is an ongoing issue for many people. That’s disheartening.

Oh well, time to try a 3rd party solution like the HD Fury I guess.

Bought the most expensive TV and most expensive sound bar I’ll probably ever buy and they can’t work together without third party hardware. What a disappointment.

Many, many people struggle with HDMI issues across all manufacturers. There are some vaguely specified details with respect to HDMI and each manufacturer makes some assumptions about how to deal with situations. When something goes wrong each manufacturer claims “never seen that before, not our problem”, yet many issues silently disappear after the next update. And, the situation can also go against the user. After an update something might not function well. The industry is struggling with this. HD Fury has been a good solution for many. The TV that I’m using does not have an ARC channel and HD Fury solves this issue.

Recently a firmware update for my SAMSUNG Neo QLED 4K UHD QN85A (QN75QN85AAFXZA) purchased Sep 12, 2021 (364 days ago!) and malfunctioning in regard to audio reliability was released.

I applied it without much hope as it didn’t indicate it addressed any issues like I was experiencing, but since that firmware update even the worst of the audio issue offending apps/sources seems to have have gone away.

I’m cautiously optimistic this has been resolved!

My TV is on firmware T-NKM2AKUC-2101.0. BT-S

I recently encountered an issue where a SAMSUNG TV remote would cause a SONY TV in another room to turn ON, but could not turn OFF that SONY TV. It turned out that the cable boxes and a shared DVD player were communicating over HDMI CEC, causing the issue. The system had been working fine for many months.