Have you tried removing the Boost and connecting wirelessly to your network? You can also try connecting a single speaker that is NOT a surround or Sub to the network to see if that helps.

Thanks & Yes, but then I still cannot see all my speakers, have to reboot.
 

But trying again, just without boost things run on a mix of WM:0, WM:1 & WM:2.

My WiFi is pretty good but I used to like speakers to be on Sonos net which was rock solid but now not so much.

Have just tried rebooting all & removing boost.  But just getting a bit annoyed with having to reboot all the time, never used to have to.

Something you may want to try as you are on S1 is to reserve IP addresses for all Sonos devices. The router’s DHCP Settings page should tell you how to do that.

Once done, power down all Sonos, reboot router and Controller device, then power the Sonos back up.

Thanks Stanley, I used to do this with my old BT router but haven’t figured out how to do it since moving to Sky, but hadn’t needed to until recently, but will try & work out how to.
 

I have moved everything off Boost on to WiFi as Polis-3015 recommended.  Seems to be okay ish so far, apart from when using speakers in group mode playing everywhere music lags at the start of a track but then plays okay.  Will test again tomorrow on different WiFi channels & try the IP address thing.

I am on S1 as don’t really want to get rid of my old Play 5, plus have heard lots from people having a nightmare with S2.  Until very recently my Sonos had just worked on S1.

The router change may have activated the IP issue, folks have done a lot of looking and no specific failure has been pinpointed.

I unwired all my wired Sonos and am now WiFi only and I’m quite happy that way, I’m on S2 though.

When grouping if you start the Group with your newest and/or best connected one the Group may be more stable.

Doing some more tests on the group mode & it seems to happen more on the high quality streaming services like Qobuz, and plays on my 2 ones first & the lag is on the other speakers.  Once playing it is okay, but if I select another track it lags again.  If I pick a standard streaming service like Amazon it doesn’t seem to happen.  Just frustrating as Sonos working with Qobuz was why I bought Sonos in the first place & it used to just work fine.