I've had my Belkin F5D6231-4 ver.2000 wireless router for over two
years and the VPN has been flakey. Only connecting 25-50% of the time
and always dropping after 5-10 minutes. In that same time, I had an
AirCard ($$) and dial-up (slow) which never had problems so I knew it
wasn't my laptop or the software. I thought it was my ISP or the
distance from my wireless until I ran across the "VPN over NAT - Issues
with Cable Modem/DSL Routers" article at:

I adjusted the DHCP Lease from "forever" to "2 weeks" as suggested in
the article and it connects great and stays connected.

It was unclear who maintains that web page and if this is even the
correct group to post to but a big THANKS to whoever.