Did you try port forwarding?
If you and your brother is using a Local Area Connection (Both of you sharing the same router), then you could just connect with your local IP's.
To figure that out, go to your command prompt (Windows key + R, and enter in "cmd"), and in there type "ipconfig".
You might have to scroll up, but look for the internet adapter that you use (whether it be Wireless LAN adapter, or an Ethernet Cable), and find "IPv4 Address". This address is your local IP.
Now that isn't even port forwarding.
Portforward has a really great list of guides to help you porting for online play.
Just... don't forget to make your internal IP static for port forwarding to work after you restart your computer.