Hi, i just tried to post a reply to an old thread but apparently it was too old to be replied too ! Anyway, it might be usefull to someone so i thought i'd add the info as a new thread:
Hi, an old thread i know, but i just went through this process with a UK D-Link DSL g604t today and this worked for me.
Up/downgrade the firmware to FW_V1.00B02T02.UK.20050815 Available via the d-link uk site (follow the instructions too !!!!!).
Don't set any security yet, just enable the access point, and don't change the ssid. Make sure dns, dhcp are all enabled.
Now let your wii try to find the access point and test the connection. This worked for me.
Download the update that is offered to you. After this, power down the wii, wait 20 sec's or so then power up again. Now test an online channel. If this does not work, check you followed the firmware upgrade properly inc a factory reset after the upgrade.
However, as most user's of this router know it is best to manually set the dns address on each node (pc/laptop/wii) and disable dns forwarding on the router once your wii has connected,updated and you have tested a few channels.
This stop's the need for a router reset every now and then.
You can(should) also now start setting up your mac address filtering, then test, then your wep or other security, then test.
Different results are all too possible, so please post any experience.
Best of luck.