I ran into a variant of this issue, here were the characteristics:
- User was able to successfully connect to a named instance, for example, connections to
Server\Instance
were successful
- User was unable to connect to the default instance, for example, connections to
Server
failed with the OP's screenshot regarding SSPI
- User was unable to connect default instance with fully qualified name, for example, connections to
Server.domain.com
failed (timeout)
- User was unable to connect IP address without named instance, for example, connections to
192.168.1.134
failed
- Other users not on the domain (for example, users who VPN to the network) but using domain credentials were able to successfully connect to the default instance and IP address
So after many headaches of trying to figure out why this single user couldn't connect, here are the steps we took to fix the situation:
- Take a look at the server in the SPN list using
setspn -l Server
a. In our case, it said Server.domain.com
- Add an entry to the hosts file located in
C:\Windows\System32\drivers\etc\hosts
(run Notepad as Administrator to alter this file). The entry we added was
Server.domain.com Server
After this, we were able to successfully connect via SSMS to the default instance.