This is a common problem with LinkSys devices. LinkSys does something funky with the UPnP implementation. I had a WRT600 N that would not auto configure. I have since moved to a D-Link DIR-855 and the auto configure works great.
There are two main things that need to be done to hand configure the router. Both these items are Port Forwarding schemes (SSL and RDP, if memory serves) that you mus manual enter for the router.
I will look up the ports and amend this post with more detail tonight when I am at home and can look up the info.
-Martin EX475 + 11TB, 2 GB mem, LE-1640, HP 3.0 Upgrade, External DVD (USB) PC's: Windows 7 64 Pro, Laptops: Vista Home Premium (32), XP Home SP3 Network: DLink DIR-855
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