Make sure that your login credentials are correct and have not expired.
Check your Internet connection.
Remember that the VPN is not accessible from on campus or from a campus Internet connection.
In case the user is having an issue accessing the server after connecting to VPN, make sure to put "@sgf" followed by user's BPL when the system asks for the credential. For example, if the user wants to get onto \\trace server, then the user will have to put BPL@sgf and his/her password.