unable to map \\umbrel2.local\music to my Sonos

The software version isn't very important, the SMB version is, that will be 1, 2 or 3.

If you are on the S1 Sonos software you need the SMB 1, S2 will work with 2 or 3.

https://support.sonos.com/en-us/article/add-your-music-library-to-sonos

Try it without the “.local”.  \\umbrel2\music or //umbrel2/music depending on which controller you’re using. If that doesn’t work, see if using the ip address works. //xxx.xxx.xxx.xxx/music

Definitely try using the IP, Sonos has had some inconsistencies with share names for a while now....

Thanks for your quick replies. Much appreciated. 
I have mapped the Umbrel2.local to a windows pc and it works. I have also tried multiple variations of ip vs umbrel2.local vs umbrel2. 

I have 2 play:1 speakers, where one is from 2013 and the other is from 2018.
Could that be the issue it is too old to have SMB3? 

Which Sonos software are you running S1 or S2, that matters (see my earlier post) not directly the speakers.

Some Sonos speakers only run S1, some only S2 and some both but it is the software that matters here.