I have my iTunes library ion my iMac shared with my Sonos via SMB share, which has been mostly working fine. I had to switch to this SMB share setup from the traditional about a year or so ago (maybe less) due to the way you changed your sharing permissions. The new protocol would not prevent my iMac from sleeping when playing music. Switching to SMB share solved that issue. However, now I have recently started having issues with the SMB share:
Lately, after indexing my music collection my Sonos for some reason is no longer able to connect to my library when playing music. I can workaround the issue by re-adding the library all the time, but this takes hours and is a HUGE inconvenience. Why is this happening suddenly and how do i fix it?