I had a recent problem when my Sonos setup suddenly lost connection to my server (running Samba)

Turns out that the latest update to Samba disables (the now deprecated) version 1 of the SMB protocol which Sonos relies on.

The workaround (should anyone else have this problem) is to edit the smb.conf file with the following:

Code:
#  Enable SMB v1 for Sonos

ntlm auth = yes

This goes in [global] section

(The comment is so you remember why you introduced a potential security risk back into your system!)

The long term solution is for Sonos to update their firmware so it doesn't rely on v1 - but I guess if that was easy, they would have done it by now!