Instructions
Make sure your access point, such as a router, is turned on and that the network is working.
Move the Wii closer to the access point or re-orient the Wii so that there is nothing between the console and the access point. As a general rule, try to keep no more than two floors or walls between the Wii and the access point.
Check if your router has the latest firmware update. You can find this information from your router manufacturer's website or your Internet service provider, if you got the router from them.
If it does not already, set your router to broadcast its Service Set identifier (SSID) by entering the router's setting from your base station (usually your computer). You can also try manually entering the SSID in the Wii. Go to the "Manual Setup" option in "Connection Settings."
Assign the Wii a static IP address. Find the available range of IP addresses in the DHCP information in your router's settings. Next, go to the "Manual Setup" on the Wii as in Step 4 to enter this information.