These days, many ISP's provide cable/DSL modems with built-in router, Ethernet switch, and WiFi access point. These all-in-one devices may be convenient, but they can leave the security of your network in the hands of your ISP rather than yours. (Many ISP's limit your ability to update firmware or view or change configuration options on hardware they provide.)
Rather than running your network on a device that you don't own or fully control, supply your own router/wireless access point and disable those functions on your ISP's equipment.
