VPN Connection thru a 678 ADSL router

[admin_2]

How do I configure a 678 ADSL router/Modem to pass PPTP VPN traffic. I have a VPN appliance on the inside lan and want to access it from the outside address. I used this VPN appliance on a Cable modem and it worked fine. I tried usig nat to forward tcp port 1723 but that didn't do it. I am guessing that I am having trouble with the GRE(47) protocol.

[drolemc]

The default setup of the PPTP Windows client uses TCP 1723 and GRE. There are no ports associated with the GRE protocol. Thus, if you are behind a PAT device, the setup will not work. Please confirm if you have NAT Overload or PAT configured. If so, you will need to remove it.