My ds lite's wi-fi gets connection problems a lot. Mainly when I want to use Animal Crossing Wild World. But for some reason, it just doesn't work. Maybe it's the provider, but I keep entering the right WEP and it still won't work!
Are you far from your router? As i've come to notice ACWW requires a lot more signal strength than most games to connect, like MKDS, when I have 2 bars with MKDS, I have 1 with ACWW, 1 with MKDS (sometimes even 2) and I cant even connect with ACWW, try getting closer.
Also the actual error you're getting may be helpful to help me help you.
I go to copper, and it says it can't connect. Then he says I should go to my wi-fi settings, so I do. Well, then it says connection test failed and I try searching for the router, it finds it. I enter the correct WEP password, and then text the connection. No success. right after that, I tried pokmon diamond wi-fi. It works perfectly. Same spot and everything. I emailed nintendo and asked about it, i haven't replied. Did they cut the ww server?
No WW's server is still up, try restarting your router or removing any firewalls, also you may have to manually input your IP/Subnet/DNS codes yourself, are you using a 2Wire? My freind had this same problem with a 2Wire router.