Have you tried wiring it directly to your router with an Ethernet cable? There isn’t enough information to make a well educated guess, you may be better off if you call Sonos Support directly to discuss it.

There is no Ethernet port on the Roam.  Sonos Support was booked up last night.  No reps were available and the Chat bot was not much help, either.  So, I tried the community.  Thanks.

I have the same error. No solution found so far. Been around the factory reset etc loop several times.

I was home alone when this was happening and trying to do it with my Google Pixel phone.  My wife came home and tried the update with her iPhone.  It went through and was done in a few moments.  The Roam has worked ever since.  Apple bias, I guess.  Good luck 

Thanks Bpittman, A two phone technique helped me, but in a different way, as described below. I contacted Sonos support by chat. My Roam problem was complex so was advised to call support with Case number provided. 40 min wait but support was good. Summary of problem and solution:

Diagnostics revealed (to support) that my Roam was not able to communicate fully with my Eero 6 router and this was preventing the Roam from receiving a necessary Update which, in turn, was preventing the Roam from being added to my Sonos system. We tried numerous work-flows that did not solve the problem, but the following method did work:

Bypass the Router by using two phones and a hotspot:

Phone 1 contains the hotspot with mobile data (4g) on (so acts as a proxy router).

Phone 2 has WiFi connection to Phone 1 hotspot (Sonos requires WiFi).

Phone 2 has Sonos app installed. Create a new Sonos system and add the Roam as the only component.

Follow instructions to Update the Roam.

At this point the Roam has the latest software installed.

Restart the Sonos app and connect to old / main Sonos system.

Add the Roam to the main system.

Everything works as it should.

Thanks to all community contributors above and Sonos support.