After NETH8 migration - SAMBA shares on Windows cannot be accessed via the usual domain name

Maybe it helps to add some samba options for Mac

See also Configure Samba to Work Better with Mac OS X - SambaWiki

Does it work with IP like \\192.168.0.1\share or name like \\nsdc-mysrv\share?

Are there dots in the usernames? Does it work with a username without a dot?

Which Windows version are you using? Did you try another Windows client?

A Windows client could get confused when connecting to the same share with different users so tests won’t work anymore.