[Samba] Linux Mint 19.1, Samba 4.7.6 & WIndows 10

[Thomas Rieff]

Which shows you are running as a standalone server. 
You should remove the '@' from the 'valid user'. 
Does the user 'gc55_data2' exist on the Linux Mint machine & on the 
Windows Computer ? 
I know that the group 'gc55_data2' will not exist on the Windows 
machine, but does it exist on the Linux Mint machine ? 

Rowland, 
There is no user gc55_data2, it is a group only for this share 
and it does exist on the Linux Machine. 
So is valid users in conflict with force group? 
Should I delete the valid users line entirely? 
Any other suggestions for proper authentication of users would be appreciated. 
Thanks for your help! 
Tom 

Thomas Rieff 
GreenCare 
1717 3rd Avenue 
Mankato, MN 56001