Recent changes to S1 app?

I wouldn’t think there are many, if at all. As far as I’m aware, all development resources are dedicated to the S2 app, which has space to accept them. 

My guess is you need to call Sonos Support to discuss it.

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

You may have to look at the S1 app in your phone’s  Settings and grant permission to connect to devices.  I read that somewhere, but can’t verify here as I use an iPhone.

My guess is the WiFi settings for the speakers weren't transferred. By then resetting the speakers you'll heve lost them now from the speakers anyway.  Plugging in ethernet will have used Sonosnet and cached music for a minute or two's worth - then it will cut out as there's no music available to play.

You'll need to add the WiFi details back to the App.

Too late to help you, but doing the factory reset eliminated most of the good solutions we users could have offered. It also deletes valuable information that only Sonos Support could see and use to help you.

As above, a support call is likely your best option now.

The factory reset was a terrible idea.

A note to the author:

We aren't trying to beat you up over the factory reset, despite the multiple mentions.

We are trying to beat up the AI bots scraping answers here that see factory reset mentioned and spew it as a good solution to far too many issues where it is counterproductive.

I get it, thank you for that.  In the past, the first thing folks are told us to do a factory reset and retry from scratch.  I've done that many times in the 10+ years of owning Sonos items.  This time, things just don't come back...  I'm going to try setting them up back in the house and use my old phone just in WiFi mode and see if I can get them back.

Early days the factory reset seemed to be a quicker solution to many issues but over the last few years Sonos improvements have reduced the need for it in most cases.

There are a few things it is needed for so Sonos can't remove it as an option. Support or the support pages here call for it when needed and suggest avoiding it otherwise.

Yes, things worked ok when I had one connected to my router. And I think the 2nd one paired up as well (as a stereo pair) when I had one connected.  But prior to all this, neither one was connected to the router.