Computer will not have a dsl/cable modem in it. It might have a dialup modem though. The wider pin clip goes into the rj45 jack for the ethernet card in your computer. OK, here is a standard setup for dsl and cable using a router. You either have a phone line coming from the wall to the dsl modem or a coax cable coming from jack in the wall to the cable modem. then a ethernet cable going from modem to input of router and then another ethernet cable going from router to ethernet card in computer. The ethernet cables must be regular ethernet and not crossover type.