Have you called Sonos Support directly to discuss it?

When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

I used to be able to use the Roam connected to iPhone hotspot and play Spotify hands free. But now I can’t seem to get the speaker to play music. Sure I could play by Bluetooth but then anything I do on my iPhone would be coming out of the roam speaker and that won’t work. Has anyone gotten it to work lately?

Is this different to your first post on this thread?
 

What did Sonos support say when you contacted them? 

I doubt Sonos Support would provide any help as using a mobile hotspot is an unsupported network setup.

It’s working now. Sonos support had me disable and enable the Sonos skill for Alexa and it works. After that I enabled my hotspot, connected to it using a second iOS device with the Sonos app and it now works.