What is the difference between a modem and a router?

Are a modem and a router the same thing?

No. A modem and a router do two different jobs. The modem connects your home to your provider’s network and brings the internet in. The router shares that one connection with every device in the house, by WiFi and by cable, and makes the WiFi. Many homes have both in one box, which is why the two words get mixed up.

• The modem brings the internet into your home. It connects to your provider’s network over whatever line you have and turns that signal into something a computer can use.
• The router shares it. It takes the one connection from the modem and passes it to every phone, laptop and TV in the house, by WiFi and by network cable.

The confusion comes from the fact that the two jobs are very often done by one box. That box is properly called a modem router, but most people, and most providers, simply call it “the modem”. So when someone says their modem is playing up, they nearly always mean the box that makes the WiFi, and when the WiFi is the trouble, that is a job for a WiFi technician.

Modem and router side by side

Compared on	Modem	Router
What it does	Connects your home to your provider's network	Shares that connection between your devices
What it connects to	The line coming into your home	The modem on one side, your devices on the other
WiFi	None	Yes, on nearly all home routers
How many devices	One, by a network cable	Many, by WiFi and by cable
Protects your devices	No	Yes. It has a firewall between your home and the internet
On its own, you get	Internet for one device	A home network with no internet

What is a modem?

A modem is the device that connects your home to the internet. Its name comes from what it does, modulate and demodulate: it converts the signal on the line outside into data your equipment understands, and back again.

Different lines need different modems:

• Phone line (DSL and VDSL). Used on the old ADSL services and, on the NBN, on fibre to the node and fibre to the building.
• Cable. Used on coaxial pay TV cable, which on the NBN is HFC.
• Fibre. The box that ends a fibre connection does the same job for light.
• Mobile. A 4G or 5G modem connects over the mobile network using a SIM card.

A plain modem has one job and usually one network port. Plug a single computer into it and that computer is online. Nothing else is.

What is a router?

A router is the device that creates your home network. It takes the single connection from the modem and shares it with everything in the house, and it lets those devices talk to each other, so a laptop can find the printer.

It does four things:

• Shares the connection between all your devices at once.
• Makes the WiFi. The WiFi name and password you connect to belong to the router.
• Directs traffic. It keeps track of which device asked for what and sends each reply to the right one. Think of it as the traffic controller for your home.
• Guards the door. Its firewall stops unwanted connections from the internet reaching your devices.

A switch does none of these; it only adds ports, and how a network switch differs covers when you need one.

Types of router

• WiFi router. The standard home router: WiFi plus a few network ports.
• Wired router. No WiFi. Used in offices and cabinets where everything is on cable and the WiFi comes from separate access points.
• Mesh system. Several units placed around the home that work as one WiFi network, for houses one router cannot cover. See why mesh WiFi keeps disconnecting for how to set one up properly.
• 4G or 5G router. A router with a mobile modem built in, which takes a SIM card. See how to choose a 4G router.
• VPN router. A router that can send all of the home’s traffic through a VPN service.

On the NBN, which box is the modem?

This is where it gets confusing in Australia, because on most NBN connections the modem is not yours. NBN supplies it.

Which NBN have you got?

FTTP HFC FTTC FTTN FTTB

Fibre to the premises (FTTP)

NBN's box on the wall is the modem. The box your provider sent is working as a router, even if everyone calls it the modem, so any router will do.

1. The line inFibre, to the NBN box
2. NBN's boxThe NBN box on the wallThis is your modem
3. The box your provider sent A router This makes your WiFi
4. Your devicesPhones, laptops and the TV, by WiFi or by cable

HFC

NBN's box on the wall is the modem. The box your provider sent is working as a router, even if everyone calls it the modem, so any router will do.

1. The line inThe pay TV cable, to a round wall plate
2. NBN's boxThe NBN box on the cable wall plateThis is your modem
3. The box your provider sent A router This makes your WiFi
4. Your devicesPhones, laptops and the TV, by WiFi or by cable

Fibre to the curb (FTTC)

NBN's box on the wall is the modem. The box your provider sent is working as a router, even if everyone calls it the modem, so any router will do.

1. The line inYour phone line, from the pit in the street
2. NBN's boxThe small white NBN box on the phone socketThis is your modem
3. The box your provider sent A router This makes your WiFi
4. Your devicesPhones, laptops and the TV, by WiFi or by cable

Fibre to the node (FTTN)

There is no NBN box, so the box you plug in does both jobs. It has to be a modem router made for a VDSL2 line, or it will not connect.

The modem is inside your own modem router.

1. The line inYour phone line, to the phone socket
2. Your own box A VDSL2 modem router, into the phone socket This is your modem This makes your WiFi
3. Your devicesPhones, laptops and the TV, by WiFi or by cable

Fibre to the building (FTTB)

There is no NBN box, so the box you plug in does both jobs. It has to be a modem router made for a VDSL2 line, or it will not connect.

The modem is inside your own modem router.

1. The line inThe building's phone wiring, to the phone socket
2. Your own box A VDSL2 modem router, into the phone socket This is your modem This makes your WiFi
3. Your devicesPhones, laptops and the TV, by WiFi or by cable

Which box does which job on each type of NBN

Your NBN type	The modem is	What you plug in
Fibre to the premises (FTTP)	The NBN box on the wall	A router
HFC	The NBN box on the cable wall plate	A router
Fibre to the curb (FTTC)	The small white NBN box on the phone socket	A router
Fibre to the node (FTTN)	Inside your own modem router	A VDSL2 modem router, into the phone socket
Fibre to the building (FTTB)	Inside your own modem router	A VDSL2 modem router, into the phone socket

So on fibre to the premises, HFC and fibre to the curb, the box your provider sent is working as a router, even if everyone calls it the modem. On fibre to the node and fibre to the building, it is doing both jobs.

That matters when you buy your own. On the first three you can use any router. On the last two it has to be a modem router made for a VDSL2 line, or it will not connect. Not sure which NBN you have? See which NBN connection you have, or check your address on NBN Co’s map. For what to look for in a replacement, see the best modem for NBN. And for the lights on NBN’s box, see NBN connection box lights.

Do you need both?

You need both jobs done. Whether that takes one box or two depends on your connection.

• You have an NBN box. The modem is already there. Add a router.
• You have no NBN box (fibre to the node or fibre to the building). You need a modem router, or a separate VDSL2 modem with a router behind it.

One box or two?

A combined modem router is simpler: one box, one power point, one set of lights. For most homes it is fine.

Separate boxes are worth it when:

• The WiFi is the weak point. You can leave the modem where the line comes in and put a better router, or a mesh system, where the house needs it.
• You want to upgrade one without the other. WiFi moves on faster than modems do.
• You want features the provider’s box does not have, such as a guest network, parental controls or better control over which devices get priority.

Setting up a router

1. 1

   Connect it

   Run a network cable from the NBN box, or the modem, to the router's internet port. It is usually marked WAN or Internet and is often a different colour from the others.

2. 2

   Power up in order

   Switch on the NBN box or modem first and wait for its lights to settle. Then switch on the router.

3. 3

   Follow the maker's setup

   Most routers are set up from a phone app. If your provider needs login details or special settings, they will give them to you.

4. 4

   Set the WiFi name and password

   Choose your own. Do not leave the ones printed on the box.

5. 5

   Change the router's own password

   The password that gets you into the router's settings is separate from the WiFi password. Change that too.

6. 6

   Test it

   Check a device on a cable first, then on WiFi in the rooms you use most.

If you would rather not do it yourself, home tech support covers setting up a new router and getting every device back onto it.

Keeping your router secure

The router is the front door of your home network, so a few minutes here is worth it.

• Use strong passwords for the WiFi and for the router’s settings, and make them different.
• Use WPA2 or WPA3 security. Never run an open network, and avoid the older WEP setting.
• Keep it updated. Makers release updates that fix security holes. Turn on automatic updates if the router has them.
• Leave the firewall on.
• Use the guest network for visitors and for smart devices you do not fully trust.
• Be careful with third-party firmware. It can add features, and it can also open holes if it is not kept up to date.

When something is wrong: is it the modem or the router?

Knowing which box does which job tells you where to look.

• No internet on any device, on cable or WiFi. The connection coming in. Look at the modem, or the NBN box, and its lights. See why modem lights are on but there is no internet.
• Internet on a cable, but not on WiFi. The router’s WiFi. If moving or restarting it does not help, have the WiFi looked at on site.
• WiFi in some rooms and not others. Coverage. The router’s position, or the house needs more than one WiFi point.
• Connected to WiFi but nothing loads. See WiFi connected but no internet.
• Devices drop off when a lot is going on. An old or underpowered router, or two routers fighting each other.

A restart is still the right first step: switch both boxes off, turn the modem or NBN box on first, wait for it to settle, then turn the router on. If it still drops out on a cable after that, the fault is in the line or the NBN box rather than the router, which is work for an internet technician, or on the copper types an NBN technician who tests the line to the boundary.

Check your speed first Test on a cable plugged into the router, then on WiFi. If the cable is fast and the WiFi is slow, the modem and the line are fine and the router or its position is the problem.

When to replace a modem or a router

• It is many years old and your plan is faster than it was built for.
• It does not suit your NBN type, for example after an upgrade to fibre, when a VDSL2 modem router is no longer needed and a good router will do more.
• It cannot cope with the number of devices in the house.
• It no longer gets security updates from its maker.

For what to look for in a replacement on each type of NBN, see our pick of modems for the NBN.

A new box is not always the answer. If the internet drops out on a cable as well as on WiFi, the fault is in the line or the NBN box, and a new router will drop out just the same.