I'm assuming you are talking about a VPN connection to your machine correct? If that's the case, open up your router firmware and go to the port forwarding section. Then you have to forward the appropriate ports to the machine specified as the server. I don't recall which ones they are exactly, but a google search should clear it up (a quick search and I came up with:500, 1701, and 4500 not sure if that's right though) . You may also have an option in your router configurations to enable L2TP/IPSec passthrough, or you can put it in the DMZ. It's been a while so hopefully I'm not blowing too much hot air.