The device could well be on WiFi. Is it WM:1 in About My System? If it’s a Move then that’s expected behaviour.

Thanks for the reply @ratty.

The device is WM:0

It is a Play:1 speaker

There are no entries in the network matrix for this device.  Seems like it is not in the STP network.

I have no idea what’s happened to this speaker - a reset doesn’t help solve it.

Is it wireless or wired? What does /proc/ath_rincon/status show? 

@ratty - it is now connected by wire to my home network.  Here is the status:

all other speakers in my system show a different operating channel (if that is relevant). Every other speaker says channel 2437 except the one above.  All others show this:

Is this any help?

Thanks A.

Change your SonosNet channel to 1. See if the Play:1 rejoins the party. You might need to powercycle it. After that you can switch SonosNet back to ch 6. 

@ratty that’s absolutely spot on!  Thank you so much for sharing that information.

I changed the SonosNet channel to 1, the “solo” Play:1 rejoined the party as you suggested (without needing a powercycle), I left overnight and everything looked great (matrix completely green).  Then I changed the SonosNet channel back to 6 and the solo Play:1 followed the other speakers onto the new channel.  Unfortunately they left a different speaker behind when I changed channel to 6 (this was then reporting Operating on Channel 2467 and WM:1).  So I changed back to Ch 1 and everything now looks great again.  Seems like there might be a tendency for a speaker to get “left behind” when switching SonosNet channels - not that I change channels frequently - but at least I now know how to fix it!

Once again, thanks for your help @ratty - much appreciated!

If a speaker ended up on WM:1 (at 2467MHz) then it flipped to WiFi. This is quite feasible under some circumstances. To avoid it, remove the WiFi SSID from the Sonos Network settings, unless of course you have a Move which requires WiFi.

The ‘getting left behind’ phenomenon cropped up on another recent thread. It’s most peculiar, since one would have thought a ‘left behind’ unit would scan all 3 available SonosNet channels looking for the system, especially after a reset/re-add. I wonder whether a unit left powered off during a SonosNet channel change is now getting left behind. In my experience this never used to be the case.

“To avoid it, remove the WiFi SSID from the Sonos Network settings, unless of course you have a Move which requires WiFi.”

@ratty is this just a question of hitting the minus symbol next to the WiFi SSID in the System\Network\Networks section of the App?  I don’t have a Move.

Thanks A.

Yes that’s it. If there’s a minus symbol then the SSID is not in use by Sonos and can be removed.

Are there any downsides to removing the SSID?  In terms of App reset or speaker reset / power cycle?  Or might this actually help the network stability by removing the option to flip to WiFi and cause a disconnected speaker to seek out the active SonosNet channel?

No downsides.

It’s always recommended that you don’t store WiFi credentials in the system unless you actually need them, e.g. for a Move, or because you deliberately want to run the system in Mixed Mode for some reason or other. It aids stability, preventing the system from flipping a node onto WiFi. 

No downsides.

Thanks for the reassurance!  I hadn’t realised that by having this SSID listed (presumably from when I very first configured my system using only WiFi) it could be used by a node instead of the SonosNet.  Makes sense though, thanks for explaining.  I’ve deleted the SSID and will be interested to monitor my system stability going forward!