this an addendum to my recent post regarding upgrading Play:1s to Era 100s which appears solved.

My old Play:1s are now in a different room. These are available as a speaker pair in the Sonos app but do not show as a playback option in Apple Music Airplay.

I much prefer using Apple Music for playback control, Sonos too laggy. 

I suspect i will need to power down speakers, router etc However i have a Sonos Move in another part of the house which shows up with no issues.

Im using Netgear Orbi WiFi.