Try connecting the speakers over a different WiFi channel, or band. So as an example, perhaps see what happens if you put all on the 2.4Ghz band, using a non-overlapping channel - 1, 6, or 11 and then play the Bluetooth audio whilst BT paired to the left speaker (if stereo paired), or to the ‘group co-ordinator’ (if grouped). You could also reduce interference by setting the band channel-width to 20Mhz only.

Another helpful step will be to ensure that both speakers have an SNR level of 45dB, or higher, as mentioned in this Sonos support link:

https://support.sonos.com/en-us/article/understanding-the-network-details-section-in-the-sonos-app

That’s nothing to do with Sonos, but is down to the player, WMP in this case. Perhaps start with this Microsoft link to try to remedy the issue:

https://answers.microsoft.com/en-us/windows/forum/all/windows-media-player-will-only-play-one-song-at-a/1bc8947f-b83a-432a-bd64-ec0bf088c136

Again this might be the player, or the file resolution - Sonos products on S2 support up-to 24bit 48kHz files only.

Also see this link:

https://www.leawo.org/entips/how-to-play-flac-in-windows-media-player-1373.html

Hope that assists.

Thank you for you reply, Mr Griffiths. Here is what I checked so far:

1. Switched to 2.4GHz, Channel 11 (20 MHz width) on my Wifi router - problem still persists. Wifi SNR is 47 dB (Right) and 50 dB (Left). Not sure how Wifi is supposed to affect Bluetooth connection. Are you expecting some jitter increase on BT?
2. What is ‘group co-ordinator’ and how do I set it up?
3. Regarding FLAC playback, the files are 16bit 44kHz, and the codecs for FLAC are installed. I can play the files with WMP on my PC with no issues.

Thanks,

Pavel

If your WiFi is using the 2.4 GHz band, i.e. variants 802.11b, 802.11g or 802.11n, it is possible that Bluetooth, which uses frequencies of about 2400 to 2484 MHz and WiFi in the 2400 - 2500 MHz region, may sometimes interfere with each other. It’s worth trying a different channel or band for that reason.

GC is the first device in the group - the one that receives the BT transmission in your case and passes it to the other grouped/paired speakers.

Here’s a Sonos support page showing the file types that Sonos supports…

https://support.sonos.com/en-us/article/supported-audio-formats-for-sonos-music-library

I can only assume something is going awry, perhaps caused by transcoding within the WM App. Maybe try the same .flac tracks with a different brand of speaker using the same connection (if practicable) and see what happens in that case. If the issue persists then it maybe best to first reproduce the issue on your Sonos device, then immediately submit a Sonos system diagnostic report from within the Sonos App, note it’s reference and then contact/chat with Sonos Support via this LINK to discuss the matter in detail and see what the Staff can perhaps then suggest to resolve the matter.

Hope that helps.