I just got my Wii today and tried to get online. I got the "cannot connect" error even though it detected my access point just fine. I have my wireless security as 128bit WEP and all my other wireless devcies work fine, but the Wii did not.
I first tried resetting the access point, changing the WEP key, etc. and none of that work. I then disabled all security and that worked, so at that point I knew it was not a Wii problem. I then enabled the 128 WEP again.
After trying 13-character keys and 26-character keys, I just happened to try something that seemed a little backwards.
On my Belkin access point, I can enter in my WEP key from a single phrase (string of characters). My expectation was to provide that pass phrase to the Wii for it to work, but that did not work. The admin for the access point shows me the HEX version of my pass phrase - a bunch of pairs of letters/numbers.
I entered THE HEX VALUES as the pass phrase for the Wii and that worked!!
So when the Wii askes you for your 128 WEP key, it is NOT the phrase you typed to generate the hex key - IT IS the hex key.
I hope that helps those that might be misunderstanding stuff they are reading but feel they are close.