I've gotten my VPN server up and running on my Windows XP Pro machine. Within my network I'm able to connect to my VPN server with a VPN connection, however, once I am outside my home network, I cannot connect and seem to be getting error 721 while trying. I've forwarded necessary ports on the router's firewall and enabled PPTP passthrough. I'm running a WRT54GL Linksys router, and I keep on coming up with error 721. Where am I going wrong? I feel like it is something with the router not allowing a VPN server to be hosted behind it. Clients can connect out to an offsite VPN server, which is what the passthrough is for, but it doesn't work oppositely. Any help would be much appreciated guys.