VPN Error 800

VPN Error 800:

Unable to establish the VPN connection. The VPN server may be un-reachable, or security parameters may not be configured properly for this connection.

Solution:
1) Make sure no other secure software blocks your access, for example, if you use Norton secure software, you may need to add the remote client's IP so that the client can access.
2) If you can establish the VPN from the desktop at home but not from the laptop. Make sure no security software like Microsoft OneCare software that blocks the GRE.