The next time it occurs, submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it. They should be able to see in the diagnostic what caused the Sonos to start playing, what it thinks is playing, and how to stop the event. 

Just as a random thought, I wonder if it would occur if you remove the connection to the DJ mixer. There have been other cases of TVs or cable boxes that start up and play ‘something’ while they update their firmware. Not sure that this is what’s going on, of course, Sonos would be able to tell you the source, but it’s a possibility. 

The DJ mixer is not hooked up.  There’s a portal for it for which I can plug XLR wires in to it to link it but it’s not in use.  Strange. 

Ah, well, it was just a thought. Still, the diagnostic data, which only Sonos has access to, should be telling. 

But that needs to be done within 10 minutes if the event correct ?

If you have “Autoplay” enabled and there is a transient picked up on the Line-In connection, the player will start. I don’t recommend keeping an unterminated cable connected to Line-In or anything that is powered, then connected to Line-In. If this cable falls onto or is pushed into a noise source (by pet, rodent, child), Autoplay will trigger the player. Another point to consider is a failing device connected to Line-In and the player is simply passing on what it receives.

In general, 10 minutes is the likely time limit for data stored in the diagnostic. Sonos has never revealed any specifics about that, I assume it really depends on which data you’re tracking. It’s possible sometimes it just stores the last event, other times it’s a rolling time related entry. Your guess is as good as mine, though, I don’t have access to them, either, so I’m just guessing. 

When Sonos employees suggest a diagnostic, they usually use the 10 minute time frame as a reference. 

I always assumed that there was a dedicated amount of space dedicated for logging on the devices.  As new log records come in, older records are overwritten.  How fast that happens depends on the level of current activity.  Sonos feels that there always enough space for 10 minutes of activity, but it wouldn’t surprise me if there can be much more than that, depending on specific speaker and activity.

I think that there is ‘coarse’ and ‘fine’ data. Coarse data would be IP addresses, version numbers and such. Fine data would be recent network data struggles. The fine data could begin to scroll after a few minutes. There are varying estimates between 10-15-20 minutes for the fine data scrolling. I always use the conservative 10 minutes

Indeed it was the “auto play” feature that was causing this to happen. Thank you for your help.