SMB server should enable IPv6 by default
I have an OmniOS 151038 host that is doing ZFS-based sharesmb. Yesterday I configured IPv6 for it. The windows 10 hosts had no problem continuing to mount SMB/CIFS shares but the CentOS boxes weren't happy about it:
CIFS: VFS: Error connecting to socket. Aborting operation.
CIFS: VFS: cifs_mount failed w/return code = -2
Removing the server's IPv6 address from DNS has them working again. However, that's not a good long-term solution to this problem.