How to Fix Client and Server-Side VPN Error 800

A Virtual Private Network provides a secure connection between a local client and a remote server over the internet. When you attempt to connect to a VPN and cannot, you receive a VPN error message. There are hundreds of possible error codes, but only a few are common. VPN error 800 "Unable to establish the VPN connection" is a common problem that occurs when you work with virtual private networks. Unfortunately, this error code doesn't explain why the connection is failing.

Error 800 occurs when you are trying to establish a new connection to a VPN server. It indicates that messages being sent by the VPN client (you) are failing to reach the server. Many possible reasons for these connection failures exist including:

• The client device lost the connection to its local network
• The user specified an invalid name or address for the VPN server
• A network firewall is blocking the VPN traffic

Check the following to address any potential reasons for this failure:

• Confirm that the network connection between the client and server is functioning properly. You can attempt to ping the server if you aren't sure, although VPN servers can be configured to ignore ICMP requests. Retrying the connection after waiting a minute or two can work with sporadic network outages. Attempting a connection from a different client device can also help pinpoint whether the connectivity issue is specific to one client or if it is a widespread problem.
• Use the correct VPN server name and address. The name a user enters on the client side must match the server name set up by a VPN administrator.  Given a choice, users can opt to specify an IP address instead of a name. It's more common to mistype an address than a name, however.  VPN servers may also have their IP address changed occasionally, especially DHCP networks.
• Make sure your firewall isn't blocking VPN connections. To determine whether a client firewall is triggering VPN error 800, temporarily disable it and retry the connection. Firewall-related failures indicate a need to update the firewall configuration with additional settings specific to the port numbers the VPN on that network is using—usually TCP port 1723 and IP port 47 for Microsoft Windows VPNs. Home network administrators normally perform these changes on a broadband router.

The server may have too many clients already connected. Server connection limits vary depending on how the server is set up, but compared to other possibilities, this is an uncommon problem. You can't check this from the client side of the connection. The server may be offline, in which case, the delay in connecting should be a brief one.