Andrew
It's hard to diagnose from here but....
The way I'm set up:
The computer hfs is on is connected to the WRT54G by ethernet cable,
The network card properties is set to a specific ip, 192.168.1.10, subnet mask
255.255.255.0, gateway 192.168.1.1. In DNS I have a host name (name of the
computer) and my dns server addresses from my isp and thats all.
The router in basic setup has starting ip address and max number of dhcp users
set to the max number of devices, wired and wireless I have, plus static dns server addresses
from my isp.
In router firewall everything is checked except NAT redirection.
In Apps & Gaming, start and end port is same (your 31028) ip is (your 192.168.1.10) enable
checked.
If the computer HFS is on is wired then the wireless router settings wont effect it.
In hfs set to expert mode be sure hfs is switched "on" and port is set to port you set in router.(31028)
An address of
http://192.168.1.10:31028 in your browser should show you hfs.
An address of
http://your numerical external address:31028 in your browser should also.
WRT54G list's external ip on status page. I'm on cable, so my external ip rarely to never
changes, even though its dynamic. (i don't know anything about dsl, though)
If it still doesn't work try shuting down windows firewall AND all wireless devices. Un plug
them if possible.
Wireless devices set to connect automatically will grab the first address available from the router,
usually the lowest numerically. I set my hfs computer's lan static address to the numerically highest
available from the router. If a wireless has grabbed the address, in my experience, nothing else can use it.
Hope this helps. Please let us know what happens.