It can be very confusing trying to determine the difference between a modem, a router and wireless gateway as it pertains to Internet access in a typical home. I’ll explain in simple terms what the differences are so it will make more sense.
A modem is a device that directly receives a signal transmitted from your ISP provider and converts that signal into a signal that a device (typically a desktop or laptop) can understand. The modem must be directly connected to your device using an Ethernet cable in order for that device to receive the signal from the modem. For example, an Internet-ready desktop would connect directly to the modem using an Ethernet cable; one end connecting to the modem and the other end connecting to your desktop giving you access to the Internet. This kind of connection is typically known as a “hardwired” connection. A modem does not have wireless capability, meaning the only way to access the Internet using a modem is to be directly connected to it. Typically, you can only connect one device using this type of connection when using the modem only.
A wireless router is a device that connects to a modem with an Ethernet cable and then allows multiple devices to connect to it. So a router expands the number of devices that can connect to the Internet at one time. This type of router can broadcast a wireless (Wi-Fi) signal that wireless devices such as tablets, smartphones and laptops can “see” and connect to and access the Internet. This is one of the primary benefits of using a Wi-Fi router.Typically there are four to five Ethernet connections on the back of a router that allow you to phycially connect devices such as a desktop directly to the router using an Ethernet cable.
A wireless gateway is a modem and router combined into one unit. These are very commonly used now by ATT and Comcast and can be set-up very easily, especially when setting up your Wi-Fi settings and connections for the first time.
*Note: Many wireless gateways now also have a third built in voice modem for Internet telephone service.
So there you have it. So there are definite differences between a router, modem and wireless gateway. Understanding these differences will help in making more sense of how these devices work in a home network set-up.