Are you connected via wireless? If so go into your router settings and set it to DMZ... That might help... For many routers, you usually get to the router settings by pointing your browser to your routers IP address (something like 192.168.0.1) and then entering a username and password. Also go to http://www.speedtest.net/ to get a general idea of your connection speed and go to your Wii's settings and check your connection there.
Another thing is that your router might be too far away or be getting some interference. (Microwaves, Cordless Phones etc.).
You could also release and renew your ip address from your ISP but I'm not sure how to do this on the Wii really...
One thing for sure, if it is your connection, you could get a wired connection. That usually will help.
Other than that, you could call your ISP and complain that you have a poor connection and see if they can see anything on their end... If you have a DSL, Cable, or Fios connection I doubt you aren't fast enough unless you live out in the country because your proximity to your ISP and also to Nintendo's servers can affect your connection as well..
If none of that works, I would contact HVS or Nintendo and see if they have any ideas.
Now Playing!
^ This is you!
