SSMS: Windows Authentication from a non-domain joined computer

When trying to connect to a domain-joined Microsoft SQL Server 2017 with a domain authentication (user account belonging to the same AD Domain as the Microsoft SQL Server) from a non-domain joined computer or a computer joined to another non-trusted domain, you get a “login failed” on every connection attempts.

The solution (or workaround) is to use the Windows Credential Manager to pre-configure the domain user account to be trusted by SSMS with the following steps:

1. Open Credential Manager (type Credential Manager from the Start Menu)
2. Click “Add A Windows Credential”
3. Populate the network address field with the name and port number of the SQL instance you wish to store credentials. For example: MyMSSQLServer.domain.org:1433 (1433 is the default port, you may need a different port, especially if you are connecting to a named instance).
4. Populate the “User Name” including the domain name: “DOMAIN\Username”
5. Enter the “Password”
6. Click OK

Done! Restart SSMS, try connecting to the remote SQL Server from your non-domain joined machine and this time your login should work!