DMZ(Doesn't Mean Zilch) your 3ds. Lets your 3ds bypass your wireless security.
If you don't know how go here and tell the rep to do it. Also,tell the rep you want to skip port forwarding and shit and just do a straight up DMZ.
If that doesn't work try another wireless router
My 3ds friendcode: 5413-0232-9676 (G-cyber)