What often resolves this particular issue is a reboot of the players, particularly the main HT player (Playbase), so I would perhaps just try that to begin with.

Edit: Ensure the WiFi adapter has not been switched off on the Playbase too (if wired).

I had rebooted the surrounds. 
I will also reboot the playbase (and sub) & try again. 
 

Wireless is enabled on all, even for the ones that are wired (playbase and sub are wired). 

Is there any actual need to wire your Ones and Sub to the LAN? Those devices will normally communicate to your Playbase over an Ad-hoc 5Ghz direct (fast) wireless connection - it’s better for the surrounds to communicate directly to the main player, rather than their communication going via the wired network through your router/switch? It’s probably the latency of the wired network here that’s causing the delay/sync issues. I would personally opt to uncable the Sub & Surrounds and just leave the Playbase only wired to the LAN and see if that perhaps improves things.

OK. I disconnected the sub from Ethernet. 
I rebooted playbase/sub/surrounds. 

Only the playbase is wired now. 
Strangely enough the network matrix does not show the sub & surrounds being connected to the playbase. 
The sub connects to the upstairs beam. 
The surrounds connect to the fireplace room beam. 
Both those beams are also connected to Ethernet. 

Does the 5 GHz connection not show up on the network matrix?

I will see if the issue with the surrounds shows up again.

I believe the surrounds usually just show as being connected to an undefined 5Ghz adapter? (Not sure?) You should still see the devices in the grid though both across the top/down the side. Note: I think some of the newer Sonos devices from the Beam (gen1) onwards no longer report their status within the matrix display anyway.

The surrounds and Sub should show as being connected to an “undefined” column in the matrix.

Newer Sonos devices don’t show their Noise Floor or OFDM ANI level in the left hand column, but they do still report the Inbound/Outbound signal etc within the actual matrix.

Disconnected & reconnected the surrounds & subs again. All only connected wirelessly.

They still show up connected to beams in other rooms in the network matrix (there is no undefined column).

Music playing is still out of sync between playbase and surrounds.

If anyone from Sonos is on this thread, I created a diagnostic in the failing state (playing music with surrounds out of sync); number: 536583753

Why are they “connected to beams in other rooms”? They should only be driven via the Playbase. Or do you only mean in the matrix? 
 

When you “disconnected and reconnected” did you also power off Playbase and surrounds, then ensure Playbase was fully restarted before powering up and adding the surrounds?

Maybe a silly question, but do you definitely have them ‘bonded’ to the PlayBase as HT ‘surrounds’, rather than being ‘grouped’ with the PlayBase?

Paste a screenshot of the network matrix. 

Why are they “connected to beams in other rooms”? They should only be driven via the Playbase. Or do you only mean in the matrix?

Yes, I mean in the network matrix. Based on earlier comments the surrounds should not show up as being connected to anything else than to the playbase that they are associated with (as they only have one radio; they cannot connect to both 2.4GHz and 5GHz at the same time).

Maybe a silly question, but do you definitely have them ‘bonded’ to the PlayBase as HT ‘surrounds’, rather than being ‘grouped’ with the PlayBase?

Definitely they are connected/bonded as surrounds to the playbase.

So based on the information so far they are not connected over the 5GHz link to the playbase?

My devices:

• Living Room: Playbase+sub+surrounds (playbase wired)
• Bedroom: Beam+surrounds (beam wired)
• Fireplace: Beam (wired)
• White: Play:1
• Kitchen: One
• Move

Network matrix:

Is your Playbase turned on? It doesn’t appear to have any connection?!

How is the Ethernet cable in the Playbase connected back to your router? And are you positive you haven’t disabled WiFi on the Playbase?

My initial thoughts is that the WiFi on the Playbase is either switched ‘off’, or it’s adapter may ‘perhaps’ have developed a fault. Maybe try toggling its WiFi off/on again in the Playbase room settings and ensure it’s left set to ‘On’.

What happens if you uncable the PlayBase from the LAN?

Is your Playbase turned on? It doesn’t appear to have any connection?!

It’s turned on alright; watching TV right now & sound is coming out of the playbase.

How is the Ethernet cable in the Playbase connected back to your router? And are you positive you haven’t disabled WiFi on the Playbase?

WiFi is turned on on all the devices (as is the recommended settings; even for devices that are wired).

The fireplace beam is directly connected (through unmanaged switch) to the router.

The playbase is wired through moca (which is functioning OK); then upstairs over ethernet cable to the bedroom beam.

I will try to only connect the “root” device (the fireplace beam) wired next (leave playbase & bedroom beam wireless).

oh yes, I see the Playbase in the left hand column now. Skipped that by on my initial glance.

Is sound also coming out the Playbase Play:1 surrounds when watching TV?

I’m with Ken on this one, it looks like the WiFi adaptor in the Playbase has a fault; your Play:1s are getting their signal from the Fireplace Beam, rather than the Playbase, hence the sync issues…

No the Sub and surrounds aren’t connected to the Playbase over 5GHz.

If they were, I’d expect the matrix to look like this (the undefined column is my surrounds and Sub connected to an Arc). It looked similar when I previously used a Playbar, and I assume would be the same for your Playbase.

I’m with Ken on this one, it looks like the WiFi adaptor in the Playbase has a fault; your Play:1s are getting their signal from the Fireplace Beam, rather than the Playbase, hence the sync issues…

Generate a Diagnostics report and contact Sonos support. 

@RobertJS,
Because the Sub is connecting via Bedroom and the two Surrounds are via Fireplace, I’m thinking there’s possibly an issue with the WiFi Adapter on the Playbase - it would be helpful to know what happens when the wired connection is removed from the PlayBase.

Was this an already known issue by the way? What caused you to wire the two Surrounds and Sub to begin with, had you experienced connection issues before deciding to wire them?

Is sound also coming out the Playbase Play:1 surrounds when watching TV?

Yes, sound is coming out.

I’m with Ken on this one, it looks like the WiFi adaptor in the Playbase has a fault; your Play:1s are getting their signal from the Fireplace Beam, rather than the Playbase, hence the sync issues…

The playbase wireless interface indeed seems to be the cause. It’s not working. After unplugging the ethernet cable and rebooting playbase it’s gone from the network (the sonos app can’t find it anymore; it’s gone from the network matrix).

I’ll see if I can get the wireless working again (connect ethernet again; toggle WiFi off, then on again).

If I can't get it back alive time to contact Sonos support...

You could try unbonding it’s Surrounds and Sub and then trying a factory reset of the Playbase - it ‘might’ cause its adapter to spring back to life.

Because the Sub is connecting via Bedroom and the two Surrounds are via Fireplace, I’m thinking there’s possibly an issue with the WiFi Adapter on the Playbase - it would be helpful to know what happens when the wired connection is removed from the PlayBase.

Yes, playbase WiFi seems to be the issue (see me reply above).

Was this an already known issue by the way? What caused you to wire the two Surrounds and Sub to begin with, had you experienced connection issues before wiring them?

Surrounds have always been wireless; I wired up all devices that could easily be wired trying to offload as much as possible from wireless to wired. Has always worked fine.

I’m pretty sure this has been working fine for a long time (5+ years). Noticed the out of sync issue recently. It likely started failing sometime in the past year. I don't play music that often on that setup & the surrounds being out of sync is not always easy to notice if it is TV surround sound.

You could try unbonding it’s Surrounds and Sub and then trying a factory reset of the Playbase - it ‘might’ cause its adapter to spring back to life.

I’ll try that next. First watching some TV on the setup now; I’ll live without the surround for a little bit.

At the risk of repeating others, the Playbase’s wireless is broken. Its outbound signal strengths are all 00, and all STP port states are Undefined. 

Hello @RobertJS , thank you for submitting diagnostics. I had a look and it appears your Playbase is experiencing a hardware failure.
Please contact Sonos Support and provide the diagnostics number 536583753.