I have a Linksys DSL router and have had similar problems connecting to my own FQ server. However, the problem seemed to go away when I used the internal IP ( address rather than the public DSL IP (the one listed on the Server List). Try playing the game on the FQ server, just to make sure everything is cool. The next step in figuring out the problem is to get a packet sniffer like Ethreal.

When the flash client first comes up, it makes an HTTP GET request to the FQ server to get messages of the day and the copyright info. If you don't see this request getting answered by your FQ server, then your network setup is wonky.