Try removing the Ones as surrounds in the Sonos app, swapping the Ones (left speaker is now the right speaker, right speaker is now the left speaker), and re-add them as surrounds.

If this doesn’t work, disconnect the Beam from ethernet and see if a wireless setup makes a difference.

Thanks for the suggestions. Have removed/swapped/re-added as suggested and have spent the last few hours watching some shows without issue.

Will see what happens whilst everything is idling overnight and, if anything has dropped offline by the morning, I’ll follow the next step re: removing SonosNet from the equation.

Good news - looks like removing/re-adding might have done the trick. Still connected after 10 hours overnight. Will put them back to proper left/right orientation tonight and see how things go.

Thanks again for the suggestion 

Damn - I spoke too soon. Just applied the 15.3 update and the right surround has dropped off again within an hour (also switched speakers back to proper L/R orientation earlier today). Will re-investigate.

Could be an issue with your router’s assigning duplicate IP addresses in error, or continued wifi interference . 

At the very least, I’d try a network refresh, by unplugging all Sonos device from power, then rebooting your router. Give the router a couple of minutes to come back up before plugging back in your Sonos. 

Thanks for the suggestions. Unfortunately I already tried that yesterday (it’s buried away in all the waffle in my original post ). All my devices have reserved IP addresses, and I’ve thoroughly checked for conflicts. Yesterday I turned off every device in the house, restarted the router, then switched on only my Sonos gear and my phone (I needed the phone to use as a controller to check what was happening). The speaker had disconnected again within the hour.

When I get time, I’ll disconnect the Beam from ethernet so that everything connects to my router directly instead of using SonosNet.

I’m currently in the middle of repeating last night’s test and reversed the speakers again, as I’m interested to see if it’s just happening on the same physical speaker, i.e. I’ve temporarily assigned the problematic rightmost speaker as the left surround instead to see if the left surround now drops out rather than the right. I was hoping this would have happened when testing last night but annoyingly everything stayed connected overnight!

I’m also hoping Sonos can take a look at the diagnostics I sent yesterday - 522827366 - a few minutes after the speaker disconnected

And as if by magic… the LEFT surround has just dropped off (i.e. the same physical speaker that was the original problematic right surround yesterday.)

New diagnostics sent: 1873586997

The only Sonos folks here in these Forums are moderators, and not Sonos Support folks. Those moderators certainly help out where they can, and do an excellent job, bur it’s not their main function. You’d get much faster response if you were to call Sonos Support directly to discuss those likely very useful diagnostics. 

Thanks for the heads-up - didn’t realise these forums weren’t generally monitored by the Sonos Support folk.

And for what it’s worth, my apologies for missing the fixed IP settings comment in your first post. I’ll admit that I dont always re-read every single post in a thread….

Hi @pjn 

Thanks for your post!

I can’t verify directly, because the same speaker was missing from both diagnostics, but the fact that the same physical speaker dropped off after swapping them round certainly suggests there’s something going on with it. There’s an amount of transmission errors between the Beam and the surrounds, so I would like to see the electromagnetic environment improved a little, but your tests, I think, have revealed something else going wrong.

I recommend you get in touch with our technical support team who will go through some real-time troubleshooting with you and get a diagnostic from the affected speaker which should identify which direction to move in from here.

I hope this helps.

Thanks for your response and initial observations, Corry. In hindsight I should have sent another diagnostic with everything working for comparison - sorry!

First thing this morning, I disconnected the ethernet cable from the Beam and rebooted everything so that SonosNet isn’t being used any more. This was approximately 13 hours ago, and so far everything has stayed connected. Now I’ve said that, it’ll probably break within a minute of me sending this post 

Anyway, I’m going to give it another 24 hours or so before calling the technical support team, as I’m pushed for time today and tomorrow, plus I’m interested to see if the problem reoccurs using normal wi-fi. Then at least we’ll have a complete list of scenarios when it happens.

Thanks again for everyone’s suggestions.

OK, final update just to put a tidy close to this!

It’s now been over 40 hours since I stopped using SonosNet and swapped to using my router’s Wi-Fi for all devices. In that time I haven’t noticed a single disconnection and everything seems to be working fully again.

I’ve no particular reason to return to the SonosNet configuration, so more than happy to remain on my router’s wi-fi as long as everything keeps working 

Thanks again for everyone’s input and suggestions over the last few days.