the router will have an IP address to let you look at the management console
it is probably 192.168.0.1 (or it may not be - sometimes it is written on the modem/router somewhere or it is in the manual) (other ones to try are 10.1.1.1 or 10.0.0.1)
you will have to put in a username and password - so you better have a look at the manual if you can find it