Wi-Fi basics and how to secure your wireless network

How Wi-Fi works

An access point broadcasts a network name (the SSID). Devices connect using radio waves and then behave as if they were plugged into the network with a cable.

2.4 GHz vs 5 GHz (and 6 GHz)

Security checklist

1. Use WPA3, or WPA2 with AES if older devices need it. Never WEP or "open".
2. Set a long passphrase: four or more random words is easy to type and hard to guess.
3. Change the router's admin password from the default.
4. Create a guest network for visitors and smart devices, separate from your computers.
5. Turn off WPS; it has known weaknesses.
6. Update the router firmware, or replace routers that no longer get updates.
7. Don't allow remote admin access from the internet.

Slow Wi-Fi? Quick fixes

• Move the router to a central, raised, open spot.
• Use 5 GHz near the router and 2.4 GHz for far rooms.
• Add access points or a mesh system instead of turning power up.
• Plug in fixed devices (TV, desktop) with a cable.

Real-world example: setting up Wi-Fi for a small café

A café owner wants free Wi-Fi for customers. The till, the card machine and the CCTV recorder are on the same router. If customers share the main network, any one of their devices (perhaps an old, infected laptop) could see those business devices.

A sensible set-up uses two networks from the same router:

• Staff network: WPA3 or WPA2-AES, a long passphrase known only to staff, used by the till and the CCTV.
• Guest network: its own name and passphrase, printed on a card at the counter, with access to the internet only.

The guest passphrase can be changed every few months without disturbing the till, and a former employee's phone stops working on the staff network once that passphrase is changed after they leave.

Try this: on your laptop, open the properties of the Wi-Fi network you are using and find the "Security type". If it says WEP or open, change it in your router settings today.