Power down all Sonos, reboot router, power up the Arc and then your other Sonos.

Thanks. I did as you suggested with no results. I am only connecting two Sonos products. The Ar Ultra and the Gen 2 sub.  My wife has the older S1 app and she has speakers in the other rooms that she controls. Those are not in my app at all.  I am stumped as to what to do next.

I did notice something.  In my frustration I was turning the sub on and off with the slider in the app. When the sub slider is on the Arc Ultra  seems to have a cutoff a bit above  50hz which makes sense. 

When I turned the sub off with the slider the bass on the Arc Ultra improved quite a bit. Louder and went  down to slightly below 40hz. If someone thinks their Ultra is weak on bass that would be something to check.

I tried starting from scratch.  I got the 1101 error. I followed the instructions given on the SONOS site but I still can not get the sub to work.

A call to support might be in order, likely a long wait on hold though.

I’m too old to wait very long.  BUT I DON’T HAVE TO!!!  I got it working. Unfortunately I’m not sure exactly how so I can’t leave anything advice.  I kept playing around and cussing and it suddenly started playiing.  Pulled the internet cord. Removed and added the sub several times. And for whatever reason reason it just decided to work.

Thanks to those wo tried to help.

I have a Playbar-Gen 2 Sub and 2x Play 1.
It's set up as 5.1 for my TV.

Just ordered Arc Ultra because I want a more detailed sound.
Since Ultra doesn't support Play 1, my plan is to remove these initially and just have Ultra and Sub connected.
How do you experience the change from Playbar to Arc Ultra?

I will eventually get 2 Era 100 or 300, and will probably also have to upgrade to Gen4 Sub.