Not the original bug reporter but I can confirm that the samba update
[sudo apt-get install samba] has fixed the problem on OS X 10.11.4
** Attachment added: "Screen Shot 2016-05-04 at 17.59.11.png"
https://bugs.launchpad.net/ubuntu/+source/samba/+bug/1572301/+attachment/4655747/+files/Screen%
Same issue here - connecting with registered user from OSX is fine, but
auth as guest fails.
Samba log (level 3):
[2016/04/26 09:57:38.879538, 3] ../source3/lib/access.c:338(allow_access)
Allowed connection from 192.168.1.43 (192.168.1.43)
[2016/04/26 09:57:38.879666, 3] ../source3/smbd/oploc
