One of the most common errors encountered when working with a VPN is error 800 - "Unable to establish the VPN connection." Unfortunately this error code doesn't tell you anything of why the connection is actually failing. If you encounter it, check the following:
→ See also - VPN Connection Error 800 (support.microsoft.com)
- Are you using the correct VPN server name? The server administrator provides this name.
- Is the Internet / network connection to the server functioning properly? You should ping the server is not sure.
- Is your network firewall blocking VPN connections? Port 1723 must be opened and Protocol 47 must be enabled in the firewall configuration settings
- Does the server have too many clients already connected (VPN server connection limit exceeded)? The server administrator can check this, but it is not a common problem.
→ See also - VPN Connection Error 800 (support.microsoft.com)

I just discovered that this error can also be caused by a corrupt LSP stack.
Also a possibility is to disable Norton Antivirus Internet protection (it probably contains a firewall)
Regarding Norton, the Norton firewall causes endless problems sometimes. I would recommend anything BUT Norton. Heck, even the built in XP Firewall is better than Norton.
This is VERY important. You may get this error if the subnet is the same on both ends.
I.E 192.168.1.xxx on the remote network you are trying to connect to via VPN and 192.168.1.xxx on the local network you are connecting from.
For this reason it is a good idea NOT to use 192.168.1.xxx on your business network which you will be VPNing to, especially if you use SBS 2003 as a VPN server.
I have to give credit to this post:
http://techrepublic.com.com/5208-11190-0.html?forumID=40&threadID=177525&messageID=2235503
Tks!
My problem is the AV System (Trend Micro).
[]s
In my case, if I reboot the PC, the connection is fine. But from time to time, it will suddenly stop working. I hope someone can tell me a solution without rebooting.
We had this issue on some of our external users. We had them update the firmware on their routers and this has fixed the issue.
If you are using an L2TP VPN you will need “IPSEC Services” enabled and started under Control Panel, Administrative Tools, Services.
HI evry body pls help me i have problem vpn error 800……..
pls help me i cant understand in english pls comments in urdu pls what shuld i do ??
I am getting Error 800 on Virtual Machine when connecting VPN, is this because of NAT?
What i am facing is rather different. If one person is connected to the VPN then no one else will be able to. For the second person to be able to connect the first person must disconnect and wait for about 30 minutes n then only the second person will be able to connect.
We trying to connect i get the same, Error 800.
@ Abbas: To solve your problem
# right-click the VPN connection,
# click “Properties”,
# click the “Networking” tab
# double-click “Internet Protocol Version 4 (TCP/IPv4)”,
# click the “Advanced…” button,
# and there it is: “Use default gateway on remote network”.
# Click OK three times.
Thank you Stephan, your suggestion fixed my own problem of being unable to VPN in to work from a hotel overseas. Unclicking “Use default gateway on remote network” solved the problem.
I used to connect to my client’s vpn in USA, with user-name and password. But now it doesn’t work from outside my office. I receive error 800. I am in India now. How do I resolve this please?
My vpn configuration is default, meaning, while setting up vpn connection on my syste, just enter vpn address, and use user-name and password with no other settings in properties.
Can you please help me?
In creating vpn server such as in XP pro, does a router required to be able to get some connection via vpn from other computer/s? my problem is i am trying to set up connection via vpn with my brother computer and making my pc as the vpn server. and still receiving error 800 – vpn server connection.
ERROR 800
You can always click on the error tab, “MORE INFO” AND IT WILL GIVE YOU THIS ANSWER.
The connection to the VPN server could not be established using either PPTP or L2TP. One or more of the following circumstances might have caused this error:
The PPTP server is not reachable. The server name you supplied might not exist, or a network component (such as a firewall) might be blocking PPTP traffic.
Verify whether the PPTP server name for this connection is correct. To check your configuration, see To configure a connection to a remote network.
Check whether Internet Connection Firewall has been enabled for this connection. For more information, see Enable or disable Internet Connection Firewall.
Contact your system administrator for additional support.
The L2TP/IPSec server is not reachable. The server name you supplied might not exist. Your connection configuration might prevent IPSec from establishing a secure channel with the server. A network component such as Network Address Translation (NAT) or a firewall might be blocking IPSec traffic.
Verify whether the L2TP server name is correct and that the connection you are trying to use has been configured correctly for your computer. To check your configuration, see To configure a connection to a remote network.
Verify whether you have a current machine certificate or that the preshared key is correct. For more information, see Enable smart card or other certificate authentication.
Check whether Internet Connection Firewall has been enabled for this connection. For more information, see Enable or disable Internet Connection Firewall.
Contact your system administrator for additional support.
make sure IPSEC services are running if you are using a pre-shared key
Thanks, worked perfectly once I added my works VPN address into the firewall and allowed the VPN elements.
@ tony:
Thanks, worked perfectly once I added my works VPN address into the firewall and allowed the VPN elements.
What did you actually Add and allow please.