I have a Samba server[1] on my network with a share configured[2] to allow access for my Windows logon user.
I can access the share from the Windows 10 machine that hosts the SMB server VM without being asked for credentials.
But another Windows 10 machine always asks for credentials (and if I provide those Windows credentials either as FreeNAS username & password or Windows user's email & password, I'm granted access as well).
The main difference I can see between the two Windows machines is that one is on the same subnet as the SMB server and one is on a different subnet. I have not (knowingly) restricted access to a specific network[3].
Does Windows prevent automatic NTLM authentication when the SMB server is located on a different subnet, and if so, can I modify this behaviour?
After countless hours of trying (and failing) to solve this on the server side, this seems like the most logical conclusion, but I have been unable to find any information about this.
Even if I'm wrong about this, what could cause this behaviour? How should I go about identifying the cause?
[1] Samba 4 running on FreeNAS 11; freshly installed in a VM on a Windows 10 machine for testing
[2] To support 'Microsoft Accounts' (Windows 8+), FreeNAS creates an alias to map the account's e-mail address to the FreeNAS username.
[3] Aside from setting up the share, I'm using FreeNAS standards for the SMB server