Tell your network admin (brother) to stop being a douchenozzle, and either nut up or shut up.
Anyone who doesn't know how to give your DS a proprietary IP address in their network isn't competent enough to be administering it. Christ on a stick.
I always get pissed at novice network 'admins' who really don't KNOW how to do the damn thing, so they just commandeer the network like you're the asshole who's gonna fuck it up.
It's not that fucking hard.
-Open up the Router Settings on a Browser
-Go to Port Forwarding/Port Triggering
-Add a proprietary address like 192.168.0.200 (Some high number that won't interfere with PCs and their automatic IP config Windows settings)
-Save your settings
-Turn on the DS
-Go to Connection Settings
-Go to "Connection 1" or whatever connection you wanna use
-Add the SSID of the Router. Confirm with OK.
-Go to Security. Type whatever connection the network is using (most use WEP but some use the latest WPA)
-Add the damn passcode
-Set the IP address to a custom address that matches that 192.168.0.200 from before.
-You're fucking done. Do the connection test.
-This is easier on the 3DS than on the DS, 'cuz some older model DS's don't use WPA (in which case you'd be screwed if that's what he's using).
I'm tired of this shit.

And they'd both be normal type, unless you gave them a double type.
Normal like Zangoose, Sentret, and Bibarel.