Restart the app and unplug the Arc from power for about a minute and try again. Also make sure WiFi is enabled on all speakers in the Sonos app.

Will give it a try and advise thank you

Tried as u suggested - not sure how to know if wi fi is enabled on surround speakers but they did chime during initial setup so I assume they are conniectd via  wi-fi 

removed surrounds from room with Arc - then tried to add back

”adding back” now for 15 minutes???

When you restart the app, does it show the Era 100s connected as surrounds to the Arc?

You might also try rebooting your router and phone.

What router are you using @39post - make/model?

I exited app

went back to settings and the speakers are connected to the devices but were playing very low volume / then figured out how to increase volume 

so I believe they are working properly now 

thank you for your assistance 

In that case, you may also find this Support link helpful…

https://support.sonos.com/en-us/article/low-audio-from-surround-speakers-when-listening-to-music