VPN Troubleshooting Guide


  1. Contact your Internet Service Provider to confirm that VPN and specifically PPTP protocols are supported. 

  2. Investigate if your local firewall or LAN configuration is affecting the VPN connection. 

  3. Document exact error message and when it appears. 

Problem: Response is slower when using the VPN than when not using the VPN.

Possible cause: Your computer is probably slowed down because your computer must perform Data Encryption Standard encryption/decryption on each packet it sends/receives through the VPN tunnel. Data Encryption Standard encryption/decryption requires a great deal of computation that isn't required when you don't use the VPN.

Solution: Only use the VPN when you need to access NAU resources that require you to be connected directly to the campus network.  

Problem: How can I tell if the tunnel is being used? How can I tell how much the tunnel is being used?

Solution: Open the VPN Client program.  Click on the tab labeled "General." You will see information about the number of data packets sent and received on the tunnel. 

Problem:  You are able to connect to your Internet Service Provider but you are unable to connect to VPN, try these: 


  • Wait and try again later, as there may have been a network disruption. 
  • Verify that you are using the correct IP address for the VPN server (vpn.nau.edu). See your client configuration for more information. 
  • Check with the Solution Center (for faculty and staff ) at (928) 523-1511 or the Student Technology Center (for students) at (928) 523-9294 to make sure that the VPN server is up and running. 

Problem: When you try to connect to your VPN server, you may be unable to connect, and you may receive one of the following error messages:  

  • Error 678: There was no answer. 

  • Error 930: The authentication server did not respond to authentication requests in a timely fashion.  

  • Error 800: Unable to establish connection.  

  • Error 623: The system could not find the phone book entry for this connection.  

  • Error 720: No PPP control protocols configured. 

Solution: Verify that you have connected to the Internet through your Internet Service Provider before you try to connect to the VPN server. 

Problem:  You can connect to the Internet but you still cannot establish a connection to the VPN server and you receive error 623. 


This problem occurs because the First Connect option is selected in Virtual Private Connection to use a Dial-up Connection and the Dial-up Connection has been deleted. 

To work around this problem: 

  1. Click Start, point to Settings, and then click Network and Dial-Up Connections. 

  2. Right-click the Virtual Private Connection in question, and then click Properties. 

  3. Select the "Dial another connection first" check box, and then select the appropriate Dial-up connection from the drop-down list box.  If there is no Dial-up connection to choose from in this location, you may have to create a Dial-up connection and then repeat these steps. 


Related Services

Available to studentsAvailable to facultyAvailable to staff

NAU's VPN service allows users to securely connect to the Northern Arizona University network.