Server is binding to internal IP rather than external

[Spinner0205]

First;
BASIC INFO
Server OS: Windows Vista Ultimate 32 bit
Processor: AMD Turion Mobile TL-60 2.0Ghz Dual Core
Ram: 4GB (3GB in 32 bit)
Game(s): Team Fortress 2
Start Up Command: C:\Server Administrator\TAGServer1 -console -game tf -secure +map cp_dustbowl +maxplayers 24 -port 27017 +exec server.cfg
Admin Mods: SourceMod

NETWORK AND BANDWIDTH INFO
Bandwidth:
Router: Belkin F5D9231-4v1(01)
Local IP of Server: 192.168.2.12
External IP: 76.31.111.228
Port Forwarding Rules: Click Here

Okay so the problem is I have forwarded all necessary ports on my router as shown above. I have tried running the Server in DMZ mode, have turned off the router firewall all together, turned off the windows firewall, and disabled DHCP, also I dont even use the +ip in the command line. If I use it with the internal IP it works fine for me, but with the external IP it spits out:

Quote:Couldn't allocate any server IP port

None of these solutions work for my server because with sv_lan set to 0 it still binds to the internal IP of the server rather than the external which means nobody but me can connect. What I have to do is completely bypass the router all together and hook up to the modem directly to get it to run like a real internet server and then it works perfectly, binds to my external IP and anybody can connect. Is there anything else I can do to get it working through the router without having to go straight to the modem?

Edit: So from reading a previous post I learned that the master servers can see a server bound to an internal IP and still see and use the external IP. However mine is not doing that and no matter what I do with the router, it still uses the internal IP.

Second Edit: Possibly as a better explanation here is the two instances of what my server says when starting up:
Behind the router:
Network: IP 192.168.2.12, mode MP, dedicated Yes, ports 27017 SV / 27005 CL

and straight to the modem:
Network: IP 76.31.111.228, mode MP, dedicated Yes, ports 27017 SV / 27005 CL

PLEASE know that before you give me a very simple suggestion like set sv_lan 0 that I have tried every simple solution I could find on the internet. Just a FEW are detailed above. I am wondering if I have overlooked anything but either way feel free to toss out any ideas.