Have not had any issues with my Sonos for a good couple of years, and not made any changes bar a BT router 4 months ago. I have a play 3 linked to router, a play bar downstairs and 4x Sonos 1s dotted about the house.

About a week ago my wife couldn’t see any rooms when opening the app on her iPad or iPhone, nor on her desktop app. I could see the system on my iPhone app and on my desktop app but not my iPad.

After unplugging the whole system and replugging back in I was able to make the system viewable on all devices, and put it down to maybe a dodgy update overnight. 
 

Today the same issue happened with my wife’s iPhone & iPad but not her desktop. I could see the system with my iPhone, and desktop but not my iPad.

I tried running through the reconnect route in the app on the iPad but it always failed when it tried to connect to the Sonos WiFi. I tried this with both the Play 3 and the Playbar.

Eventually I restarted the router which seemed to fix it, but later this evening my wife said she had lost the system again on her iPhone.

Whats going on? I’ve gone from no issues to having a really unstable system in the last week, sometimes a device finds it, some other device won’t…

We have tried forgetting the WiFi and rejoining, reinstalling the Sonos app and rebooting the WiFi.  We have no guest WiFi’s or anything of that sort. Just one WiFi that everything is connected to.