Troubleshoot VPN connections

Troubleshoot VPN connections

Troubleshooting VPN connection issues typically involves contacting your Internet service provider (ISP), your VPN server administrator, or your router or firewall manufacturer.



When you try to connect to your VPN server, you may not be able to connect, and you may receive an error message that resembles the following:

678: The remote computer did not respond.



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



800: Unable to establish the VPN connection.



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



720: A connection to the remote computer could not be established.

To resolve this issue, use one of the following methods:

Verify that you have connected to the Internet before you try to connect to the VPN server.



For more information about troubleshooting Internet Connectivity in Windows XP, click the following article numbers to view the articles in the Microsoft Knowledge Base:

314067 (http://support.microsoft.com/kb/314067/ ) How to troubleshoot TCP/IP connectivity with Windows XP

314095 (http://support.microsoft.com/kb/314095/ ) How to troubleshoot possible causes of Internet connection problems in Windows XP

If you can connect to the Internet but you still cannot establish a connection to the VPN server, and you receive error 623, see the following Microsoft Knowledge Base article:

227391 (http://support.microsoft.com/kb/227391/ ) Error message: "Error 623 the system could not find the phone book entry for this connection" when making a VPN connection

If you can connect to the Internet but you still cannot establish a connection to the VPN server, and you receive error 720, see the following Microsoft Knowledge Base article:

314869 (http://support.microsoft.com/kb/314869/ ) Error 720: No PPP control protocols configured

If you still cannot connect to the VPN server, the VPN server may not be configured correctly. Contact your VPN server administrator.



If you are the VPN server administrator, see the following Microsoft Knowledge Base articles for additional information about how to configure a Microsoft VPN server:

308208 (http://support.microsoft.com/kb/308208/ ) How to install and configure a virtual private network server in Windows 2000

162847 (http://support.microsoft.com/kb/162847/ ) Troubleshooting PPTP connectivity issues in Windows NT 4.0

299684 (http://support.microsoft.com/kb/299684/ ) Error message: Error 930; The authentication server did not respond to authentication requests in a timely fashion

If you use a personal firewall or a broadband router, or if there are routers or firewalls between the VPN client and the VPN server, the following ports and protocol must be enabled for PPTP on all firewalls and routers that are between the VPN client and the VPN server:





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Client ports Server port Protocol

1024-65535/TCP 1723/TCP PPTP



Additionally, you must enable IP PROTOCOL 47 (GRE).



For information about your firewall or router configuration, and to confirm that your firewall or your router will pass these ports and protocol, contact the manufacturer of your firewall, your router, your ISP, or your VPN server administrator.



Parts of this article referenced from: http://support.microsoft.com/kb/314076