new ERA100

Thanks! That explains it then. 
I will try without the boost connected to the system

I tried disconnecting the boost, and all units are now directly on the WiFi. Still the ERA100 will not pair with the one sl I have - I want to play the same music at both on the same time, is that not possible with these two models ?

Are you using the S1 app or the S2 app? Once plugged into power the speaker should show up in the app as a new device that needs to be added to your system/

Do you have Bluetooth enabled on your phone? You may need to have the phone right next to the 100 for it to be recognised. 

Use the “group” feature, not pair.

Thanks for your inputs. 
 

the problem is that I have an era100 which is added to the system, and this works fine. I can use it individually so to say. But when I try to group the speaker with another on (from the same system, but in another room) I get a failure description saying “not able to connect, try later”.

my existing system works as usual and I can group the different rooms if I want to listen to the same in different rooms, but with the new era100 is does not work - only individually 

hope it makes sense 

I have disconnected the Sonos boost so all products are now on WiFi 

I’ve seen cases where the grouped devices are not running the same firmware, although I’m not sure how this is possible. Try ‘playing’ something on both sets of speakers, then check for updates, and see if one or the other needs to be updated. 

I could be wildly wrong here, but the effort is small. 

Try rebooting everything byt powering down your network and speakers. Then starting with the first device, modem, modem/router combo, power it on and allow it to fully boot. Do this for everything down the chain of your network. Then starting with the main speakers, like a soundbar or Amp, power it on and allow it to fully boot, then move onto the other speakers.

Thanks guys! 
a system update solved the problem, thank you all for your help - really appreciated