I know it doesn’t work for everyone but in my room where I only use Apple TV 4K while I have change format set to DD5.1 and I turn off eArc on my tv I never experience the issue. This proved to me it’s nothing network related and most likely some kind of bug with specific formats when being switched/initialized 

does anyone experiencing the issue have an LG OLED? My system that doesn’t have the issue is a LG CX but my system that does have the issue is a Sony A9G

Here’s my latest theory:

Based on my observations, I get extended periods of stability until something ‘triggers’ the issue and then every switching activity (source, codec, app, content, etc.) brings a high likelihood of dropout. Then I do a big reboot/reset/rebuild by hard rebooting, disconnecting, unpairing/repairing and then I’m stable again for a while. 

Looking for commonalities in this thread, everyone experiencing this issue has an Apple TV 4K or Nvidia Shield and a newer high end TV that should support eARC. Although the issue occurs across more source devices, those things seem present for everyone. Apple TV 4K and Nvidia shield have Dolby Mat encoders/ decoders. They handle Dolby content by decoding on-device and sending a multichannel PCM stream rather than native Dolby bitstream unless you somehow force them down to Dolby Digital (not plus) witch is then bitstreamed. eARC support is required in the tv for multichannel PCM or else the Apple TV automatically downgrades to bitstreamed Dolby digital. It’s also a pretty specific combination of devices required to get multichannel PCM to the Sonos ARC which might explain why only some people are experiencing this. It also explains why some users have reported improvement or fully masking the issue by disabling eARC or forcing the Apple TV to Dolby digital (not plus) which would result in bitstream. I therefore think the ‘trigger’ is related to Dolby Mat/multichannel PCM. Once triggered, then you see the dropouts everywhere until you rebuild your system.
 

I’m going to try my most extensive rebuild yet and leave all sources disconnected and use the native tv apps which should give me bitstreamed Dolby digital + and atmos. If that’s stable, I’ll connect my Blu ray player and try bitstreamed TrueHD. If that’s stable I’ll connect my Apple TV’s and see if the issue reoccurs

I tend to switch my setup from time to time, but mostly I just use a Boost wired-setup off a Plume WiFi mesh router.

My ISP provided device is a VIrginMedia Superhub v5 but I just have that set to ‘modem mode’. I have 3 x 16-port switches on the LAN and most of the rooms here have wired Ethernet points, not that I use the wired LAN for any other Sonos devices (well maybe just occasionally, every now and then) . 

I choose to reserve/fix all the Sonos IP addresses and I scan/check/change (sometimes) the SonosNet channel every few months to make sure it doesn’t coincide with my ‘dynamic’ Plume WiFi, or the next door neighbours Sky router WiFi channels. 

Yes I have a C1

@Freddy45764 i agree I suspect it’s something to do with Dolby Mat. I actually kinda don’t mind forcing Dolby digital for everything now as I don’t care for the lower volume of LPCM. It’s just annoying to have to manually enable Atmos when I need it 

@Brad Porter sorry you are having problems still 

Think its been over a week now since I removed and readded the sub and I have not had the issue return below is the list of my equipment 

LGB8 65

Hdmi 1 apple tv 4k

Hdmi 2 arc

Hdmi 3 fire cube tv

Hdmi 4 PC and xbox series x on hdmi switch 

Arc is hardwired to my Gateway eero 6 pro via a 8 port switch connected to the 5g broadband router 

I have been watching YouTube prime and shows and films purchased on apple all streamed

The fault has not reappeared for me

All my speakers are using sonosnet save the moves and roams I have which are on wm:1

My arc is the sonos network provider as it's the only one wired I will do a diagnostic if it returns but so far so good touch wood 

Im with you brother. Forge forward where I have failed! 

It’s rather a strange HT issue, isn’t it? I can perhaps see why this might take a little while to resolve, as there is no clear, obvious pattern, or way to easily reproduce the issue across all our different system setups.

I think the answer is what was mentioned earlier by @jgatie and that’s to just keep submitting a system diagnostic with each report as and when the problems are seen and then wait to see what comes from that with the rollout of each new Sonos update. 

@peterbault - How have you done the ‘forcing’? 

Did you do this on AppleTV (i.e. Change Audio) or the TV (i.e. turn off Atmos, disable e-arc)?

I have noticed in the S2 App (and maybe related to what @Freddy45764 is saying) that when I am testing I either have Dolby Atmos come up or (when playing 5.1) it comes up as Multichannel PCM or something. 

Multichannel PCM x.x would be your Apple TV using Dolby mat to decode on board and send multichannel PCM stream. Atmos is a bit more complicated. When Sonos reports atmos, you’re getting one of Dolby digital +, TrueHD, or multichannel PCM with Atmos metadata attached. I haven’t found a way to tell which it is from within the S2 app. 

Except that I’m 1000% sure I’ve solved it every time I have a new whacky idea until I’m proven wrong 15 minutes later

The issue occurs for me using solely the apps in my Samsung TV. I don’t use an Apple TV. The only external device I use occasionally is a PC connected to the TV.

I’m wondering if it’s an eARC/HDMI related issue.

Windows does Dolby mat if I’m not mistaken but maybe this is the first dent in my theory. I’d really love to hear from someone who uses exclusively a Roku or something

the system where I don’t have the issue the only device I have that uses Dolby Mat is Xbox series x I think? It’s in Dolby Atmos 100% of the time though so maybe that’s why it hasn’t caused the issue? 

Ya I was thinking about your system with your Xbox. Wasn’t really sure how that device worked or if you use streaming service apps or just game on it. Interesting to hear it’s 100% atmos

Yeah all I do is game on it and you just set it to bitstream Dolby Atmos and it upmixes everything. Any content watching I use the tv apps 

I have many Apple TV’s in the house I could hook one up to my LG CX system and see if it reproduces the issue. I don’t really feel like power cycling anything in my office though haha 

Don’t do it!!! Don’t invite more pain on yourself

Yeah I have an LG OLED BX which is the step down model to your CX and I am also experiencing the issue. I tried a lot of things but I gave up and have temporarily removed the sub and surrounds and i’m just using the Arc solo.

May I ask what are your source devices?

Apple TV 4K, PS5, Sony X700 4K Blu-Ray player. The issue has occurred on all devices, including the built in Smart TV apps. Sometimes, if I need to pause content for a few minutes, it will be totally silent when I resume what i’m watching. Power cycling the Arc is the only way to get sound back. 

I refunded my Arc and 2 subs today since I was within my return period. Got really tired of Sonos not acknowledging this bug after a whole month of frustration from us. Will use my money towards a stable sound setup.

Hope you guys find a resolution soon! I’d be really upset if I couldn’t return my system due to this bug.

We too have had this exact same issue over the last two / three weeks, so glad I found this!

This is so sad - it really, in part, could have been addressed with stronger communication from Sonos. It really is a great product when working. I am just mystified why this has been allowed to run the way it has. It does not make much sense.