Over 50 Sonos devices? If that’s the case, how many do you have hardwired to your network?

Isn‘t there a limit of 32 devices per system!? 
https://support.sonos.com/en-us/article/add-a-new-product-to-an-existing-sonos-system

So I guess you have split them to more than one system….

And if the system isn‘t found it still exists and you can not add a device a second time. So what you should do is to find out about the reason why your system can‘t be found. 

Every component worked as intended, this new Sonos upgrade wipe-out configuration. Now these components will not save . Software blows up, and disappears. I didn’t try to upgrade , happened automatically. Many are hard wired.

@HankWF 

Sorry, but imho that’s too less information to help you. What about more then one system? And what about usecase of such a large amount of speakers? And most important… what in detail about network setup?

Maybe calling Sonos directly would be the better way to save time. They can help you by looking at diagnostics and if you agree by remote controlling your pc to look at network settings. 

Sorry, but I don't buy this inconsistent tale at all. Even if it's genuine, @HankWF seems to have insufficient understanding of his system for us to be able to help him.

 @Schlumpf's advice for @HankWF to call Sonos Support is the only sensible response. 

40 years in IT, no storyline here . 

There might have been an update. Last upgrade was the infamous S1/S2 split a couple of years ago.

Could you answer the questions posted by @Schlumpf ?

If you cannot see your system, how do you know there was an upgrade that took out your system since the previous evening?

You created your profile a couple of days ago, so I assume your device list is up to date.  It includes some devices compatible only with Sonos S!, and others only compatible with S2.  So are both systems affected?  Even S1?

I assume this is a technical expression from your 40 years in IT?