Do You Need a Modem and a Router?

Everything you need for the best home internet experience

Modems and Routers Look Similar, But Serve Difference Purposes

iStock/Getty Images Plus

Broadband is a necessary component for so many aspects of our digital lives. Gaming, watching videos, buying music, and even web browsing depends on it. There's a long line of equipment and services that brings all those bits to you, and two of the components closest to you are the modem and router.

What Is a Modem, and Why Do I Need One?

"Modem" stands for modulator-demodulator. When "Internet stuff" is transmitted, it was originally sent over wiring (e.g. copper). While we know that all data is represented at the end of the day as zeroes and ones, it's difficult to send something that represents that definitively over metal.

Most Modems Have One Coaxial Input and (Only) One Ethernet Output
Amazon/Zoom Telephonics

So instead, the signal is sent as either high or low, and these get translated to the ones and zeroes our computers are expecting. So, when we send data, a device needs to modulate them into the right signal strength, as well as de-modulate signals coming back.

A modem, on its own, has the ability to connect your home to that outside network, and is identified by your IP address, which is assigned by your internet service provider (ISP). If your home had only one networked device, you could plug it directly into the modem and happily surf away. However, most homes today have many networked devices, and you need a way to manage their connections to each other as well as the Internet. That's where a router comes in.

What is a Router, and Why Do I Need One?

A router is focused on local area networking, and performs the following functions for devices within your home network:

  • Manages and assigns IP addresses.
  • Acts as the domain name service, although it will look to your ISP.
  • Sends requests, such as for a web page, over the Internet on behalf of your devices and returns the results.
  • Blocks incoming requests from the Internet. More advanced routers can be configured to let select ones through.
  • Connects multiple wired devices, as most standalone routers only have one Ethernet port.
  • Some advanced routers have a built-in VPN server, allowing you to log into your home network remotely.

Do You Need a Modem and a Router?

So, to the question at hand — do you need both? If we're still thinking of these as functions, the answer is yes. There needs to be some piece of circuitry that takes the signals of your cable provider or phone company and translates them into the Ethernet most networking equipment understands. This is the modem.

For 2-in-1 Devices, Note the Coaxial Input, and the Multiple LAN Ethernet Outputs
Amazon/Motorola, Inc.

And unless you have only one device in your home (connected to that modem over Ethernet), you need something to manage local IP addresses and maybe provide wireless coverage. That's the router.

Using 2-in-1 Modems/Routers

However, that doesn't necessarily mean modems and routers have to be separate physical devices. There are some modems with built-in routing capability, and there are a couple of reasons these may be appealing.

A single device only takes up one power outlet, and you'll only need to learn how to use one interface to configure and manage your home network. Furthermore, a single device may be less expensive than the buying a modem and router separately.

Using a Standalone Modem and Router

However, there are some reasons and constraints that make using a separate modem and standalone router the most prudent choice:

  • ISP Support: Your internet service provider may not support these combined models. In fact, there's a chance you're required to use whatever modem your ISP dictates.
  • Placement: While it's convenient to have both of these functions in one device, separate devices give you more freedom of placement. For example, you might put the modem in a closet, but you wouldn't want to stifle the wireless access point in there.
  • Features: Stand-alone routers tend to have more and better features than combined models. If having VPN access, advanced routing, or the ability to connect a printer to share on the network is important to you, you're more likely to find these in a separate router.
  • Performance: If your router kicks the bucket, at least you won't be totally offline. You can still plug a computer directly into the modem. If the integrated router in your combined device goes, you're probably out of luck unless you can solder.

How to Choose the Right Device(s) for Your Network

There's a long chain of devices that work together to bring you your favorite internet videos, with the modem and the router handling key aspects of the process.

You need a device to performs both of these functions. And although it's possible for one device to act as both, there are pros and cons to having a combined modem/router versus two standalone devices. If you're constrained on the number of electrical outlets you have, for example, or prefer the easier administration of a single device, go with a 2-in-1 modem/router.

On the other hand, if you need flexibility in placement or want certain features, having separate devices is probably a better bet for you.

In the end, you should carefully plan your home network setup before investing in either option.