trying to set up a VPN server at home

I'm trying to set up a VPN server at home which uses a cable modem connection and a Netgear router. The router is set up to pass through the PPTP protocol on port 1723. The router has an IP address and gateway address. From work, I can only ping the router's gateway address. How does the VPN client get to the VPN server through the cable modem and router? Which address should the VPN client try to connect?

Suggest you try the Netgear support forum. What you need to do to make your VPN work will be Netgear specific.