Has there been a change in your network? A high probability cause for your issue is a duplicate IP address. Have you reserved IP addresses for all regular network clients?

We cannot rule out hardware failure. A couple days ago the network at my workplace went down. While it’s not a 2008 vintage network, it’s certainly not up to current standards, but it suits our needs and is normally reliable. Sometime over the weekend the router’s power supply failed. I was annoyed, of course, but it was a simple fix.

I also note that the current SONOS system discovery process as a controller starts up is a little slower than before and the controllers can be impatient. Try waiting a few seconds after that draconian message appears.

Hi Buzz, Thanks for your reply. Although I have had Sonos for 15 years my current equipment is all under 3 years old. The network has no duplicate IP addresses. I just feel the whole system/functionality/reliability has become frankly useless. If I compare it with my Philips Hue network with over 50 lights each with its own IP address I never have any issues at all. I am looking at replacing all my Sonos equipment now……..

SONOS makes heavier demands on the network than a bunch of lights. I recommend submitting a few diagnostics and have SONOS support comment. The Community regulars are not having these issues.

As an aside, Phillips Hue uses Zigbee rather than wi-fi to connect so it’s not a fair comparison.  You say that you don’t have any duplicate IP Addresses, how are you so sure as this is very difficult to identify?  Please see my post: Tips & Tricks - Resolving random issues impacting Sonos devices.. | Sonos Community

You have no way of knowing you don't have duplicate IP addresses, so I would hold off on the definitive statements.  We can help you, but we can't get past one who refuses to consider that it may be their network causing the problem.

What a load of bull**** I have done all the IPCONFIG stuff and determined there are no conflicts!!! Anyway these replies just prove SONOS has lost the plot. My whole point is that it should just work without having to be a network engineer!!!! These problems are all within the last 6 months after 14+ years of relative stability. Just an example…. Yesterday my Playlists were in My Sonos on my iPhone… today they are gone…. 100% completely unacceptable!!!!! 

I’ve been doing this for 15 years, and I can count on one hand the system problems like yours that weren’t solved by a simple procedure, and prevented from happening again by a further procedure that takes just a little more effort.  Neither of these procedures require being a network engineer.  But you seem to know better, so I’m not going to bother giving you advice.  Enjoy your non-working system.  

PS: IPCONFIG won’t show you IP conflicts, because your router table has no idea there is a conflict.  Hence the problem.  But you keep doing you.  

Once you’ve decided the problem must be e … ] or cannot be … ] you are likely to be blindsided.

I started to write a reply to your post but.... I wish you luck in resolving your issue.