At least temporarily, try wiring one Sonos product to your router with an Ethernet cable, if you can. Don’t wire a Sub, or surrounds, though. 

Then I’d call Sonos Support directly to discuss it.

When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

I’ve just found exactly this, so I’m wondering if an app update has screwed it.  I can still see my system when logging into sonos.com website, but nothing shows in the app.  Weirdly if I power on my Sonos Move it appears, but none of the other devices.  Varying attempts to uninstall/reinstall the app, add components manually, etc. all fail.

So have we got another borked app update?

Not borked for me although I get that scary “nothing found” message at all too many app starts. It usually clears and shows my gear in 5 to 30 seconds so I have learned to not panic early.

My system never appears, sadly, have left it for several minutes.  I’ve also repeatedly killed/relaunched the app, nothing changes.   :(

Maybe a power down everything, reboot the router and power back up?

If that works try assigning static reserved IP addresses to all Sonos.

Thanks, have got a bit further. On a whim I power cycled the one wired speaker (Sonos One) providing Sonosnet, and everything appeared. 
 

Still checking as it's weirdly not showing up for my partner. 🤪

I’m seeing a lot of recommendations to move to WiFi and away from Sonosnet. I think I’m putting that on my to-do list for later in the year and once things stabilize.

(App don't panic)  you are completely connected, just redo 5 tmes and it does seem to appear to work, and maybe in the distance future it will be possible to hit the app once and all good, come on Sonos I know you can do it good look every one.

Madness continues this morning.  I powered on my Sonos Move (2) this morning and it seems ‘missing’ now from my system.  Couldn’t use Alexa on it either to start music, so gave up.  Noticed 10 minutes later it’s back again, try to play to it - nothing, won’t play.  Then it disappears again.

Next up when I have time to waste on it - I’ll have to factory reset it and try again.  

Satisfaction level with Sonos is going down by the minute.  Read an article yesterday that they’re considering reverting to the ‘old’ app.  Seriously hope this is a decision reached quickly as this situation is unacceptable.  We have thousands invested in this system and it was all quite stable until very recently.  Moving to a new and larger house in a month and we won’t be investing further in Sonos equipment until this is firmly resolved.

Read about the website yesterday. This one worked just fine, so it's down to the app in my opinion. Then deleted the app and reinstalled it (several times) it still can't find the system. We also tried 2 different devices (Android and IOS) both apps do not work. Am planning to call the helpdesk and see what they can do about it.

Hi, Just got my new sub this morning so started the app, which appearantly was updated and stated that I had no sonos products. Doing a network update works fine.. it detects all the producs (also the new sub) and adds them one-by-one.. after I've clicked “done” the app still states there are no sonos products and that I am not connected. Apart from the sub, that I cannot add to the system now, the arc and one sl's work ok. But there is no way I can get the sub to add to the setup. So now i have a $700,- sub that I cannot use because of a broken app. :(

btw, If instead of doing a network upate, I select “setup a new system”.. it cant find any products..

I was always satisfied with sonos products but this is beginning to be a real sh#tshow. I am going to try factory resetting and if that doesnt work the sub will be sended back again coz now its just standing there collecting dust.

What did support say, when you called in with this issue?

I faced the same issues which are related to the app. Resetting the app, uninstall and reinstallling had no effect. Also tried factory resetting one of my products without success. However, when I installed the app on my wife’s iphone, which did not have the previous version installed everything was working. I could connect to my existing system and add the one sl back again. After various attempts on my own iphone I am also able to connect with it now.

so perhaps a fresh install on another mobile phone does the trick. Hope this helps.