Perhaps try moving the speaker nearer to the local router and see if that maybe resolves the issue.

Exactly same probablem here, only era 100 with the problem, move, roam, beam and symfonisk working well. 
Sonos technical Support does not find a Solution. 
I am totally sure is a firmaware issue of the era 100 related to airplay 1. Airplay from iPhone or iPad works ok (Airplay 2). 
Last firmware update around a month ago.

really disappointed. 

Maybe see these links & requirements for AirPlay 2 …

https://support.sonos.com/en-us/article/stream-airplay-audio-to-sonos

https://support.apple.com/en-gb/101611

Edit: Note in the first link shown above, it mentions… "You can also use AirPlay 1 to stream system audio from macOS to Sonos, but you may experience a delay, or audio interruptions”.

Airplay 1 has works perfectly good for years…today still is working in all my Sonos speakers except Era 100…

I’m sorry I can’t really add anything further, as I usually just AirPlay from an iPhone, or iPad, and that seems to be working okay. What App/source-device are you using?

iTunes running on a win 11 machine. 
Raspberry pi 5 running LMS (lyrion music server)

Airplay 2 from iPhone or iPad or macOS works ok. 
 

With airplay 1 the Sonos app shows the Era playing, but no sound is produced. 
 

thanks