This router is just killing me.

I bought the router to share internet wirelessly with
another laptop.

And it works fine.

However, I had to format my 'base-computer' and reinstall
windows. But the computer is not detecting the router in
its system, but somehow the router is still working fine.

Even when I try to install the network manager again, it
cannot detect internet connection, even though it is
connected.

This is not such a big problem, since the internet works
fine.
But the real problem is that, due to the firewall
installed within the router, I am getting an awful speed
of downloading files.

The whole internet becomes comepletely paralyzed when I
activate a p2p program which shares files with other
users. And the speed is PATHETIC.

I need to find a way to get rid of the firewall, but my
computer is not acknowledging the router in its system.

What should i do? Is there any way to eliminate the
firewall?