Hi

A few questions:

!/ So your Era 100 is working okay and you have the S2 app installed? 

2/ Is it possible to connect the Arc to your router by an ethernet cable to connect it and update the firmware?

Yes, Era100 are going great.
 

I probably can connect to the ethernet, but it would not be able to be plugged into the tv. Will this still update the firmware?

Yes, once added under settings, system check for updates.

Thanks. 
called Sonos today, I think they did something after I ran diagnostics for them. All is sorted and working great!

Great news

Same exact thing happening to my new Arc SL. I’ve also tried factory resetting the Arc, restarting router, hardwiring Arc via Ethernet, reinstalling the Sonos app. Nothing is working. Still stuck on the screen saying “There was a problem adding your Sonos Arc SL to the system.”

I can see the Sonos Arc SL when I look at my WiFi router’s configuration app. It was also able to software update itself, so it’s definitely getting internet. I also have a bunch of other Sonos products, including another Arc and all of them worked perfectly.

Any ideas what they did specifically?

None - run the diagnostics in the app and give them the number shown. They did something then I had to hard shut down the app and start the fix now again. It worked. I ran diagnostics again and she said all was good. 
 

I wonder if it’s to do with the new app….?

Experiencing the exact same thing with zero resolution at the moment.  Sitting on wait with phone support now going on 45+ min to try to better understand what’s going on. 

Factory reset for me occasionally re-pairs it and I can use it briefly but, for example, if I leave the wifi network or alternatively use my bt headphones or connect to something else non-sonos, the arc disappears in the app and I get the “No products found” message in the app even though my network router shows the soundbar on it when I check that end.  This is very frustrating, $700 soundbar and it won’t airplay.