I'm not very familiar with how VPN is set up, and in searching for help, it seems that there are many things involved. I suspect my problem is much more vanilla, so much so that people don't bother asking about it. Most responses I get are for running VPN servers behind or even on their router, so I haven't found an answer yet. The story is, I'm on a computer at home, running vpnc on Ubuntu Linux (Intrepid), connecting to a VPN server at my work office. I connect my computer directly to my DSL modem with an ethernet cable, and the vpn connects. I then installed my new Linksys WRT54GL v 1.1 running Tomato 1.25, and tried sticking that between my DSL modem and my computer, and vpnc does not get a response from the server. I looked at the traffic using Wireshark with and without the router to see what seemed to be missing. It seems to get stuck on some ISAKMP packets. My computer is sending it out in both cases, but only getting a response without the router involved. I don't see anything about ISAKMP in port forwarding. From picking up bits and pieces online, I tried turning on DMZ (which, as I understand, connects my computer directly to the Internet, so really everything should work, however insecurely, so perhaps there's some user error on another level), I tried fwding UDP port 4500, I tried turning on NAT-PMP. All are on at the same time, still no response. Any idea what I can do? Thanks.