You should check your network settings on your Nintendo system, as you cannot change your LAN ips from your router. (Especially if you have NAT or DHCP enabled.) You have to manually edit your settings from your computers or other equipment.
Just check your network settings on your equipment, should find a 'tcp/ip protocol' function or something similar to it. That is what you need to change.
Have your ips match your internal lan ip, except the last digit. And make sure you aren't blocking those addresses.
(192.168.0.2-254 or 192.168.1.2-254)
Set your netmask as 255.255.255.0
That should be most of what you need.
If you need anything else, let me know.
~~Azurith