This is probably Apple issue, but good to know:
Client 1 from Mac OS (El Capitan) connecting smb://zentyal/share , connected and everything works fine. When client 2 from different machine (does not matter, if Mac or Win) connects and add folder or file to this share, client 1 cannot see these changes in Finder. But not alwyas, sometimes information is updated, sometimes not. If information is not updated, disconnecting and reconnecting share helps and client 1 can see everything correctly again. There is some specification - if client 2 is Win and saving there MS Word file and there is character - (hyphen) used in the filename, client 1 can see in Finder only tmp file (which is MS Word creating during saving proccess and after that renaming it to the correct filename). Maybe it happens without hyphen in a filename, but not in my case. If client 2 creates new folder, client 1 sometimes see it, sometimes not.
I spent whole evening and no clue.
In the morning, with fresh mind, there was a small success. If I use old smb (cifs), everything works fine. It looks some incompatibility or error in SMB 2, SMB3 protocol from Apple? Or combination of some settings in Samba and SMB2, SMB3 Apple protocol implementation?
I don't know, because on my home Synology NAS all versions NT1, SMB2, SMB3 are working fine with Mac OS !!!! Why?
For now I "resolved" it by adding:
client max protocol = NT1 parameter in /etc/zentyal/stubs/samba/smb.conf.mas
server max protocol = NT1 parameter in /etc/zentyal/stubs/samba/smb.conf.mas
After samba reboot, clients are using NT1 version and there is no problem for MacOS connections.
Thanks for this tip:
https://forum.zentyal.org/index.php/topic,27225.msg99673.html#msg99673