SSPI handshake failed with error code 0x8009030c and The login is from an untrusted domain and cannot be used with Windows authentication

If your computer is not connected to the domain, you can get this error when you try to connect to a SQL Server in your domain with SSMS by using windows authentication while your vpn is open.

When you connect to the event viewer to access the details of this error, you will see the details in the screenshots below.

To solve this problem, you can add your local computer into domain.

Or, instead of authorizing your domain user on SQL Server, you can ask your SQL DBA team to create SQL Login.

This error can sometimes occur when connecting to SQL Server from application servers. There are two option in this case.

Your application server may have dropped from the domain,

or

The password of the user you connected to your application server may have expired.