On my samba server I had the problem, that just one user at the time could access the share. I had
security=user activated. The log file under
/var/log/samba/log.smbd said at the last line:
smbd_open_once_socket: open_socket_in: Address already in use
(Die Adresse wird bereits verwendet)
I googled it and stumbled over a very different topic describing other problems. There it was mentioned as a solution to add a user per smbpasswd. Then I realized, that I didn’t have my system user in that database.
The problem is, if the samba config requires a user to exists on the linux server, samba can log in the user only once. I think that’s because the samba runs on that user. The samba user database must have sort of a mapper interface, which maps multiple samba users to just one system user.
The console command
smbpasswd -a username resolved my issue and now I can connect from multiple computers to the share.