Server not working here, working elsewhere

[Condawg]

Alright, earlier in the week I set up a dedicated server on my computer using this tutorial. At home, it worked fine. Forwarded the ports 27000-27020, followed the tutorial, no problem.

Now I'm at my brother's house, trying to use my server. I forwarded the ports correctly, but for some reason I get "server not responding," as does a friend of mine.

Here's my required info...

Server OS: Windows 7, 32-bit.
Processor: Intel Core 2 Duo, 2.66GHz.
Ram: 2GBs.
Game(s): TF2
Start Up Command: (Set up as a shortcut) C:\Server\orangebox\srcds.exe -console -game tf -hostport 27015 +maxplayers 24 +map arena_nucleus
Admin Mods: SourceMod
IP Address for server (if it helps): 98.221.42.46:27015

Any help would be widely appreciated. I was looking forward to trying out the server on this connection, as it is better than my home connection. (Less lag for everyone else.)

Thanks =]