By the end of this lesson you will be able to
- State the one-sentence job of a modem, router, switch and access point.
- Compare wired Ethernet and Wi-Fi, and choose which suits a given situation.
- Identify the main sockets on the back of a home router.
- Explain what a network interface is and find yours in Settings on Ubuntu or Windows.
- Explain the difference between the 2.4 GHz and 5 GHz Wi-Fi bands in plain words.
The little boxes with blinking lights are the part of a network you can actually touch. Most people have no idea which box does what, so when something breaks they restart everything and hope. Knowing each box's job lets you check the right thing first, and helps you buy or move equipment sensibly.
Four boxes, four jobs
Each device has one main job. Compare them to a road system. The Modem is the slip road onto the motorway: it connects your home to your provider's line. The Router is the junction in your street: it sends each piece of data the right way, between your devices and out to the internet. A switch is a multi-way plug board for cables: it lets many wired devices share one network. An access point is the radio mast: it lets devices join the network without a cable.
- ModemConnects your home to the provider's line.
- RouterJoins your network to the internet and directs data.
- SwitchMore wired sockets on the same network.
- Access pointProvides Wi-Fi for wireless devices.
Read this figure as text
Four cards showing a modem, router, switch and access point, each with its job.
Modem: connects your home to your internet provider's line and converts the signal. Router: connects your home network to the internet and directs data between devices; it also gives out addresses and usually includes a firewall. Switch: adds more wired sockets so many cabled devices can join the same network. Access point: provides Wi-Fi so wireless devices can join the network. A typical home box combines router, a small switch and an access point, and sometimes the modem too.
In a home you usually own one box, often called a “home hub” or “Wi-Fi router”, that does all four jobs. In an office or a big house you might see them separately: a switch in a cupboard with cables running to rooms, and several access points on ceilings. Same jobs, more boxes.
| Device | Main job | Needed at home? |
|---|---|---|
| Modem | Turns the provider's line signal into data your router can use | Yes, but often built into the router |
| Router | Joins your network to the internet; directs data; gives devices their addresses | Yes, always |
| Switch | Adds extra cable sockets | Only if you have many cabled devices |
| Access point | Gives Wi-Fi coverage | Built into the router; extra ones help large homes |
Reading the back of a router
The back of a router shows the same ideas as a plug board. Look at the numbered picture, then compare it with your own router. Layouts vary by model, but nearly all have these parts.
Read this figure as text
A drawing of the back of a Wi-Fi router with six numbered parts: antennas, power socket, internet port, LAN ports, reset button and information sticker.
Marker 1: antennas, which send and receive the Wi-Fi signal. Marker 2: the power socket for the router's own adapter. Marker 3: the internet (WAN) port, which connects to the modem or the wall socket from the provider and is usually a different colour. Marker 4: LAN ports, where you plug in computers, printers or televisions by cable. Marker 5: the reset button, a small recessed button that erases the router's settings if held, so leave it alone. Marker 6: the information sticker, which prints the default network name and password.
Cable or Wi-Fi?
Ethernet sends data along a cable. Wi-Fi sends it through the air as radio waves. Both carry the same internet; they differ in how they behave. A cable is steady and fast. Wi-Fi is convenient but the signal weakens with distance and with walls, and every wireless device in range shares the same radio space.
- Steady speed, small delays
- Not troubled by walls or neighbours
- Needs a cable to the router
- A visitor must plug in to join
Best for devices that stay in one place.
- Join from anywhere with a good signal
- Speed varies with distance and walls
- Devices share the radio space
- Needs a strong password and modern security
Best for phones and laptops that move.
Read this figure as text
Two columns comparing Ethernet cable and Wi-Fi on speed, reliability, convenience and security.
Ethernet (cable): usually the most stable and fastest; not affected by walls or neighbours; needs a cable run to the device; harder for a stranger to join because they must physically plug in. Best for desktop computers, televisions and anything that stays put. Wi-Fi (wireless): convenient and works for phones and laptops that move; speed varies with distance, walls and interference; many devices share the radio space; needs a strong password and modern security. Best for phones, tablets and laptops.
Most routers broadcast Wi-Fi on two bands, which are different radio frequencies. The 2.4 GHz band travels further and goes through walls better, but it is slower and more crowded. The 5 GHz band is faster over short distances but weakens quickly through walls. Many routers show these as two names or combine them under one name and pick for you. If your phone struggles in a far room, 2.4 GHz may be better; sitting next to the router, 5 GHz is usually faster.
Network interfaces: how your device plugs in
Inside your laptop is a small piece of hardware for each kind of connection: one for Wi-Fi, one for the Ethernet socket. Each is a network interface. Every interface has its own MAC address, a unique label burned in at the factory, and gets its own IP address when it joins a network. You can have the Wi-Fi interface switched on and the cable interface unplugged at the same time.
You do not need to change anything now. Just find where your computer lists its interfaces and see which one is connected.
Find your network connections in Settings
Menu wording changes slightly between releases. If you cannot find an item, use the search box in Settings.
Ubuntu 24.04 (GNOME)
Step 1: Open Settings
Click the system menu at the top right of the screen and choose Settings, or press the Super (Windows) key and type Settings.
You should see: The Settings window opens with a list of categories on the left.
Step 2: Open Wi-Fi
Click Wi-Fi in the left list.
You should see: You see a switch to turn Wi-Fi on or off, and a list of visible networks. Your connected one has a tick.
Step 3: Open Network
Click Network in the left list.
You should see: A wired section shows an Ethernet connection if a cable is plugged in, or a note that it is unplugged. If your computer has no cable socket, this section may be missing.
Step 4: Look, do not change
Click the small cog beside a connection to see details such as its IP address and hardware address. Close the window without changing anything.
You should see: You can see an IPv4 Address and a Hardware (MAC) Address for the connection.
Windows 11
Step 1: Open Settings
Select Start, then Settings (the cog), or press the Windows key and I together.
You should see: The Settings window opens with categories on the left.
Step 2: Open Network and internet
Click Network & internet in the left list.
You should see: The top of the page shows which connection is in use, Wi-Fi or Ethernet.
Step 3: Look at Wi-Fi and Ethernet
Click Wi-Fi, then your network's name (Properties), or click Ethernet if you use a cable.
You should see: A Properties page shows the network name, IPv4 address and physical address (MAC) of the interface.
Step 4: Look, do not change
Go back and close Settings without changing any switch.
You should see: The connection is still working.
IPv4 address: 192.168.1.23
Hardware address: 5E:3A:91:C4:0B:7D (made up)
- Marker 1: A connected Wi-Fi interface
- Marker 2: A cable interface with nothing plugged in
- Marker 3: Address details for the connected interface
Read this figure as text
A simulated settings window listing a connected Wi-Fi interface and an Ethernet interface that is not connected.
A simulated settings window titled Network, with a sidebar listing Wi-Fi, Network and Bluetooth (Network is highlighted). The main area shows two rows. Marker 1 is the first row: Wi-Fi, connected to a network called HomeNet-Amina. Marker 2 is the second row: Ethernet, cable unplugged. Marker 3 is the body text: the connected interface shows an IPv4 address of 192.168.1.23 and a hardware address, both made up. It is not a real screenshot; your Settings will look different.
Common mistakes
✖ Instead of: Pressing the reset button to restart the router.
✔ Do this: Use the power switch or unplug the power adapter, wait about thirty seconds and plug it back in. Reset erases your settings.
✖ Instead of: Plugging the computer into the router's internet (WAN) port.
✔ Do this: Use a LAN port for your computer. The internet port is only for the cable from the modem or provider.
✖ Instead of: Buying a Wi-Fi extender to fix a slow connection near the router.
✔ Do this: An extender helps coverage far away, not speed beside the router. If it is slow nearby, look at the provider's plan, the router or interference first.
If something goes wrong
- I plugged in an Ethernet cable but Settings shows “Cable unplugged” or nothing happens.
- Push both ends in until they click, try another LAN port and another cable. Check the router's light for that port. Make sure you used a LAN port, not the internet port.
- Settings has no Wi-Fi section.
- Your computer may have no Wi-Fi hardware, or it is switched off by Airplane mode or a keyboard key. Turn off Airplane mode and check any wireless key on the keyboard. A desktop may need a Wi-Fi adapter or a cable.
- I see two networks with almost the same name.
- They are probably the 2.4 GHz and 5 GHz bands of your own router, often shown with “5G” in the name. Join the one that suits where you are sitting.
Key terms
- Network interface
- The part of a device, a chip or a card, that lets it join a network by cable or radio.
- Network switch
- A box with many cable sockets that passes messages between the devices plugged into it.
- Access point
- A device that gives wireless devices a place to join a wired network.
- Wi-Fi
- A way of joining a network and the internet by radio instead of a cable.
- Ethernet
- A wired way to connect a device to a network using a cable.
- MAC address
- A unique number built into a network interface that identifies it on the local network.
Practise it for real
Reading is not the same as being able to do it. Complete these on your own computer, then tick only what you have actually done. These ticks are your own honest record: nothing checks them for you.
Identify the parts of your own router
Find your router. Without pressing any button or unplugging anything, name the power socket, the internet (WAN) port, the LAN ports and the information sticker. Write down which lights are on and which cable goes where. Check whether the modem is in the same case.
Challenge: list your interfaces
Open your network settings without using the lesson steps. List every interface your computer shows (Wi-Fi, Ethernet, and any others), say which one is connected, and find its IPv4 address. Do not change any setting. Then explain to someone why your laptop can have two interfaces but be on one network.
Knowledge check
6 questions. You need 80% to pass. Mistakes here are part of learning, and you can retry as often as you like.
Summary
- Modem connects to the provider; router joins your network to the internet; switch adds cable sockets; access point provides Wi-Fi.
- Home boxes usually combine all of these jobs in one case.
- Cables are steadier; Wi-Fi is more convenient. 2.4 GHz reaches further, 5 GHz is faster nearby.
- A network interface is your device's connection to a network, with its own MAC and IP address.
- Never use the reset button for an ordinary restart.
Checklist: can you do these?
Marking a lesson as read does not prove you can do it. Skills count as demonstrated when you pass the quiz (not yet) and complete the practical tasks (not yet).
Related lessons
References and further reading
Official sources for details that can change between versions.
- Networking, web, email and chat (Ubuntu Desktop Guide) (Ubuntu)
- Wi-Fi problems and solutions in Windows (Microsoft Support)