which cable to use between router and modem
In order for devices on the network to connect to the Internet, the router must be connected to a modem. Therefore, most routers have a specific Ethernet port that is designed to connect to the Ethernet port of a cable or DSL modem. A modem is a device that provides access to the Internet (see below). The modem connects to your ISP, which typically provides either cable or DSL Internet service.