Can you connect to the same access point and play lag free? I ask this question because I have been pulling my hair out since January trying to figure out why when I connect two units to my access point and begin a race in mario kart, our entire connection slows to a crawl, upwards of 2k ping. But it's ONLY with Mario kart.
http://techforums.nintendo.com/message/62233#62233
http://techforums.nintendo.com/message/62233#62233