Are you using any WiFi repeaters or mesh points? What are you using to control the SONOS system? Which SONOS products are in your system? Are any units wired to the network? If not, wire one or more SONOS units to the network as a test.

I suggest that you refrain from Factory Reset without further consult.

I use two of the above, one as router and the second as mesh repeater (connected by cable). There is a function in the router app to activate/disable free romaing meaning that units can seemless mesh. I have tried turning off and on with no success. Same problem.

not tried connecting by cable yet. 
in my system i have:

play 1 x 5 units. 4 setup as stereo pairs. only the non stereo unit is working most of the time. About the same age.

1 x move

2 x ikea bookshelf units - works on and off

appreciate the support
 

check if you are using the latest app version and it supports all you SONOS units - except for the Move, connect the SONOS devices by cable - check your network settings: disable network isolation and avoid using ‘guest’ networks

No guest networks.

latest ios (s2) installed.

network cable is not really an optiin with almost all except for one.

Wire that one unit, if only as a test. Does the system function?

Wired one play1 in the livingroom and that works. Interestingly as its a steoro pair, both works (also the one still connect over wifi). 

At least temporarily wire the “missing” units to get them online. Since there is something fundamentally wrong with your WiFi setup as far as the SONOS units are concerned, I suggest that you keep one or more SONOS units wired to your network after you get them to connect. You can go to Settings → System → About My System to display the units currently online. WM: 0 units are using the SonosNet mesh, WM: 1 units are using WiFi, and WM: 2 is a private 5GHz connection used for surrounds and SUB’s. MOVE is always WM: 1.

I prefer to use SonosNet, rather than WiFi. While the units are online you can verify that the WiFi credentials are correct.

Use different wireless channels for SonosNet and WiFi. Set your WiFi to use channel 1, 6, or 11 and use the 20MHz channels on 2.4GHz.

Interesting, so by adding one speaker by wire they all move to sonosNet mesh? They are all WM: 0 besides the move. Where do you tweak channel for sonosmesh (edit: Found it!)? I would of course prefer to not add one by cable going forward. Not sure you can tweak the 2.4Ghz on the TP-link Deco but will give it a try.

the TP-link Deco let’s you create different networks (SSIDs)  

You can add a SONOS BOOST as the wired unit.

yes but it doesn’t allow me to tweak channel setup.

yes but I don't want to buy something for 100euros to get my system to work as it already should.

so it back to basics then and figuring out your wifi setup - you mentioned the TP-link AX6000 and TP-link Deco, while these are powerful devices they may cause interference if wrongly configured - I would first make sure you have a single 2.4Ghz network, served by one DHCP server 

So its dualband on 2.4Ghz that is working perfectly for all other units than our Sonos speakers. You can not remove dual band. Some speakers work from time to time. The Deco doesn’t have many options unfortunatley but the upside is that you also can not configure something wrong. Not sure what could possibly be incorrect in my setup. 

you could turn off the Deco access points to check how SONOS behaves on the AX6000 router - if not already done, I would create the 2.4Ghz wifi network with a different name than the 5Ghz band

Thanks, I will try that as well but it defeats the whole purpose. I would like to have an access point obviously and the same name regardless which Ghz but I understand that its about narrow it down to understand where it goes wrong. 

Given the amount of time that’s been spent “going mad” over connection issues a Boost would have made sense. Time is money. 

Well it is a matter of principle, I will not spend even more money on something that is working so bad as my Sonos speakers. I don’t think I am the only one thinking that way and having these problems without being a network r****d. 

But also the last thing I need is another unit that consumes power and space for something that should already be working.

Disappointed that I choose this ecosystem as its to expensive to restart.

Moderator Note: Modified in accordance with the Community Code of Conduct.

Feel free to defend that hill of principle. For me life would be too short to struggle.

Sonos units all prefer to remain on the same 2.4GHz channel (they communicate most efficiently peer-to-peer, especially in groups/pairs) and WiFi meshes frequently upset the apple-cart. They auto-select different channels, and sometimes attempt to band-steer devices onto 5GHz. 

By the way the power needs of the Boost are very modest: 2.3W. It can even be mounted flat on the wall.

Hi @Fritte77 

Welcome to the Sonos Community!

Please check the “meshes” section of the following post for some important info:

I hope this helps.