TRY IT IN A TEST ENVIRONMENT BEFORE
This is what I made on Nextcloud 13 and Nethserver NG 7.5.
Nethserver is configured as Local AD.
Enter as admin in Nextcloud:
Settings -> Integration LDAP / AD (on the left column) -> Expert (Above right) -> in the field “Internal user name (Attribute internal user name)” enter the following string (pay attention to the uppercase and lowercase that must be written just like this):
userPrincipalName
At this point, only all new users that will be created in Nethserver, when they are generated in Nextcloud will receive as UUID the name of the login (which also corresponds to the login, main email and home directory of the user).
Please make this change before creating users on Nethserver, preferably to newly installed servers and Nextcloud, otherwise there is a risk that you will encounter the problem reported below.
I activated the plugin “External Applications”, created a share in this way (all without " ):
Folder name: "homeuser" (is the name that is mapped in the list of folders in Nextcloud)
External storage: "SMB/CIFS"
Authentication: "Login credentials, save in session"
Host: "localhost"
Share: "$user"
Domain: "MyNetBIOSDomainName".
If you want to modify all UUID of all existant users:
PAY ATTENTION THAT IN THIS MANNER YOU WILL LOSE ALL EXISTANT NEXTCLOUD USERS CONFIGURATION AND SHARES
Enter as admin in Nextcloud:
Settings -> Integration LDAP / AD (on the left column) -> Expert (Top right) -> click the two buttons “Delete association User name-User LDAP” and “Delete association Group name.LDAP group”
(click on blurred line to see the instructions, these instructions are blurred because are dangerous!)
PAY ATTENTION THAT IN THIS MANNER YOU WILL LOSE ALL EXISTANT NEXTCLOUD USERS CONFIGURATION AND SHARES