macOS 15.0.1 cannot stream via Airplay to Era 100

In case anyone else is experiencing this, maybe I can save you some frustration. Trying to Airplay from macOS 15.0.1 to Era 100 appears to be broken. I can use Airplay from my laptop to other Sonos devices (Arc, Roam), but it fails with a generic "could not connect" error when trying to use the Era 100. Other Apple devices (iPhone and iPad) can stream to the Era 100. Just not the laptop. So it seems to be specific to macOS and not iOS or iPadOS.

I was on the phone with Sonos support for over an hour, and after making me reboot everything including my router and wifi hardware, they finally conceded that this seems to be actual bug and will have to be fixed with a firmware update.

The Sonos app still works, btw, it's just Airplay that's broken.