can only suggest trying a different port in warcraft 3. I sometimes find the act of changing it from 6112 to 6113 works. Then if it stops working to change it back.
So go into warcraft 3 offline, go to options and change the port in there.
Still not working? try even disabliing the firewall completely. I find i need to actually disable it to host (port forwarding did not work for me either).
I suspect a combination of these 2 will fix it looking at what you've already done.