[Samba] login without domain\username

[ERIC PEYREMORTE]

Hi all, 

I'm sure it's a newbie question but is it possible to allow users on computers outside domain to connect to a share just with their login instead of domain\login ? 

Ex: when a user using an off domain computer connects to \\srv-name\share, he has to prefix its username with the domain (domain\user). 

In our previous setup with samba 3, on our domain member file server we used that : map untrusted to domain = yes. 

Now we have an AD windows server 2019, several samba4 files servers and a single domain. 

I can connect to the windows server with bogus\login or plain login, but it doesn't work on file servers. 

I know i could use the UPN, but it was to make the transition easier to users (non technical). 

If it's not possible, why isn't it ? Is it something with kerberos of ntlm ? 

Cheers