Did you read Nintendo's site for this? They have game specific info.
Basically you need to port forward only the wii IP address. If you need help ask Ill walk you through it or go to Ninetendos site.
Also change the channel on the router. If its on 6 try 1 or 11.
There should be no other pc on at same time you brawl online. Lame but ..... its the way they designed it.
I got disconnected alot. I had to remove any cordless phone. If it rang goodbye game lol.
I have a 10 to 12,000 Mbps download and still dc'd. The lines shouldnt be all rolled up and on top of electrical cord.
Microwave close by? Yep dont use it either.
What controller do you use?
wii-mote is laggy as heck. Try Gamecube controller.
Royal pain but I had to do all that then it was virtually lag free.