Able to RDC but cant VPN. Need VPN HELP

[Guest]

I have 2 XP Pro workstations, both directly connected to DSL. Both have
public IP addresses. I have no problem making RDC connection between them,
but I can not make VPN connection. I have tested client work station by
making VPN connections to another XP Pro workstation without any problem. It
would seem I have a problem with the "server."

XP Pro "server" is configured to permit incoming VPN connection. Firewall
shows VPN ports are open. I keep getting an error 800.

Any suggestions would be apprecited.

 

[Guest]

update......
After some changes in the firewall, the error message has changed to 678 (no
answer)....all this while I have a RDC open and can ping the IP by name and
number.

Still looking for answers.