Lost surround and sub ( after update ?)

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.