I'll just post the link. It's
http://www.nintendo.com/consumer/systems/wii/en_na/errors/results.jsp?error_code=86420&system=Wii&locale=en_US&action2.x=7&action2.y=19 This is the part I really don't understand:
In order to solve this problem, you may consider adjusting your router's Port Forwarding settings*. Each router is unique, so consult the owner's manual for your router or contact the manufacturer for specific information on working with your router's ports. For your information:
If you are prompted for a device or profile name, you can enter anything you like (such as Wii, etc.).
The starting port to open is 1, the ending port to open is 65535 (or as high as the router will allow).
Protocols will need to be set to UDP only.
Set the IP address for the ports to forward to the same as the Wii's static IP address. If you don't know what the Wii's IP address is, the best way to determine it is by performing a manual setup: