I suspect that the Samsung is temporarily stopping the CEC ARC signal output to the Sonos. Have you updated the firmware on this Samsung, and contacted their customer service?

I have EXACTLY the same problem! Same tv (77"), same fw, same Sonos setup. Sound clips randomly but seems to always last about 5-7 seconds. Also, this never happens when using connected Series X or running 4K HDR movies or internal apps like Prime. Biggest problem is when using internal YouTube, but also using connected Nvidia Shield 2019.

To compare I have yet the exact same setup in my "gaming room". Only difference is it's I have last year's QD-OLED S95B 65", and no problems whatsoever! Have you been able to find a solution? I also use certified 2.1 fully certified HDMI cables all over. Changing makes no difference.

Edit: When gaming there is no problem on the S95C either.

Google Samsung tv and Sonos Arc issues….the list goes on and on………

Just received feedback from Samsung support:

Please try your Sonos speaker with another TV, if you can, to determine if the issue is linked to TV or speakers. If it is TV, likeliest reason is incompatibility of codecs between Sonos and Samsung TV.

Extremely helpful as expected.

Lol. Have you informed them about me having two exactly identical Sonos setups with the only difference is that the other system is connected to an S95B, as in the tv that then got "upgraded" (2023) with the S95C? And as I said, the predecessor works flawlessly with the Sonos setup. I would imagine the newer model of their QD-OLED flagship suddenly stopped working with conflicting codecs all of a sudden.

So, in short, it's on Samsung, not Sonos.

What I meant was, " I can't imagine the newer model of their QD-OLED flagship stopped working with conflicting codecs all of a sudden."

Samsung wants you to buy a Samsung soundbar, that's why Sonos products have trouble 

It’s hard to argue with you, although I suspect there is a slightly less nefarious reason behind it. My guess is they’ve extended the instruction set of CEC to make it work ‘better’ with their own soundbars, and really don’t recognize that it has messed up a standard CEC implementation. Those would be secondary to their testing…if it works with the Samsung bar, why test with others? 

I always have a hard time attributing purposely bad intentions to most companies. They all seem to be chasing the almighty profit, and sometimes miss other issues due to their focus on their own systems.

But yea… ;)

Hello, has this issue been solved in some way now ?

I have a Samsung QE55S95CATXXN with Sonos ARC and same issues here...

I am having similar issue with my Beam gen2, when it Sonos sounds great but I also stream 99% of my content via Apple TV 4K an if I’m watching a YouTube video and go back to another streaming app, say Apple TV+ that has Atmos (enabled) audio it will play PCM via TV and not switch to Sonos (CEC enabled) unless a power off (cords removed) of both TV and Beam then works again until I’m switching between apps again  

What did Sonos Support say, when you called in with your system diagnostic ?

They said the issue was noted, it had been asked of, about by other owners a think she said Samsung might’ve been aware but not 100% on that. A waiting game I think which obviously a hassle for us  

Hello, i  have fixed this issue by switching the eARC mode to ARC mode in the samsung tv.

I do not know if this has impact on the sound quality or if dolby atmos is still working but the sound now does not fall out or anymore...
 

Will try this plus try a 2.1 HDMI cable as the  Sonos provided one is capable but from research a 1.4 cable, please do not hold me to this until I attempt switch