In reply to VS4b:
Yes, usually controlled from the software on your router. This is accessed via your web browser.
You can usually get there by putting the IP address of your router into your web browser. Assuming you haven't changed this, common default addresses are 192.168.1.1 or 192.168.0.1, so try these first.
If these don't work, try the following. If you are on Windows, open a cmd window and type ipconfig. In the output, you are looking for the default gateway. If you are on a Mac, there are instructions here (second post down)
http://stackoverflow.com/questions/6782658/how-to-get-default-gateway-in-ma...
You will usually need a user name and password to log in. The default user name is often admin or something similar - the details are often on a sticker on the router or the box it came in. If you don't have these any more, there are lists of defaults for different routers on line.
The level of control available to you will vary from router to router.