If you want to reconfigure the router, you need to perform a master reset by looking for the reset button on the side with network ports. The reset button is located next to the AC port. It looks like a whole so you will need to use something very thin. Press that button for at least 20 seconds and then plug the network cable to one of the yellow ports.
Then you will need to access the router's interface by going to Start > Run > type CMD and press enter. Type ipconfig /all and locate the gateway's IP address which in most of the cases is:
192.168.2.1. Paste the IP in the browser's URL field and hit enter. By this time the router will most likely be unprotected so a password would not be necessary.
When the interface is loaded, perform the needed configuration.