Can’t help since I pitched my WD NAS but there a lot of posts here that may have your solution.

If nothing else submit a diagnostic and call Sonos Support for assistance.

Try one of these paths:

\\Mycloud\public\music

\\WDMYCLOUD\Public

\\MYCLOUD-xxxxxx\Public

And make sure your WD NAS is running the correct version of SMB and NTML, which would be v1 for Sonos’ OS called S1, and v2 or 3 for Sonos’ OS called S2. 

Unfortunately, there are some of the lesser expensive WD products that don’t allow you the capability to change/access the SMB versions. And all, or at least a large portion of WD’s NAS line are called MyCloud. There is an extensive discussion about how to set up SMB v1 in this thread.

All now sorted! Thanks for the suggestions.

I have spent ten hours on the phone with Sonos, and they could not get my brand new NAS to work. Sonos said maybe in a month an update would come out.

How did you get it “All now Sorted”?

Sadly I cannot recal the exact actions, but it was getting the web address correct if I recall(?).

I used //MyCloud-(ID number)/Public/Music) 

Mine is a WD ‘MyCloud’ NAS drive…