after S2 upgrade, “cannot connect to device”

Hi @S.SKarn, welcome to the community! Thanks for submitting a diagnostic as well but I cannot open it, maybe part of the issue. Try to reboot your router and submit another diagnostic. Check with other music sources as well and reply to us with the confirmation number again of your diagnostic. Thanks! 

Same issues here. And I have had years of issues of my speakers disappearing. My diagnostic number is: 

1167302444

Hi @User923978, welcome to the community! Appreciate the diagnostic and reaching out with us. Upon checking, yes some of your speakers are struggling to stay connected to your wireless network. Try moving the missing speakers closer to the router to prevent future drops. Also, you can try to hardwire one of the speakers to your router using an ethernet cable. The wired product will broadcast a dedicated wireless network that your Sonos products will use. This article about speakers missing from the Sonos app would be helpful to your concern. Let us know if this helps. Always here to help. 

Thank you for your help. There is one speaker that has completely dropped off too which probably isn't on the report that was sent (we have 4 speakers). 
 

Unfortunately our house, which is quite small (approx.    1,200 Sq.ft) is spread over three floors and speakers are on two of the three. The router cannot be moved from its location and there is no way to hardwire any of the speakers to it as there are no speakers on the floor where it is. So it's one of those things where the technology does not match how the location has to be setup. It's just food for thought for future investments with Sonos or other wireless speaker companies as some things just aren't meant to be!

Hi @User923978, thanks for getting back to us. I understand that it will be a little harder for you, but if it’s okay just to get one speaker and hardwire it to the router using an ethernet cable for testing purposes. So if it will gonna work, you can check our Sonos Boost that you can permanently hardwire to your router to broadcast a dedicated wireless network that your Sonos products will use. Appreciate your patience. Thanks!