Unless your router is really old or an entry-level model, it will almost certainly have both 5GHz and 2.4GHz Wi-Fi. Often called 'dual-band' it means it actually produces two different Wi-Fi networks, one on each frequency.
2.4GHz is reliable at greater distances and goes through walls and floors more easily than 5GHz, which is a lot faster (or can be) at closer distances with fewer obstacles.
Does my router have 5GHz Wi-Fi?
Unless you already know for sure that your router is a dual-band model and definitely has a 5GHz radio, it's worth checking that out first. There's no point enabling 5GHz Wi-Fi on your laptop if your router doesn't support it.
The easiest way to do that is to check its specifications online, look in the manual, or log in to the router itself and check the settings available in the Wi-Fi section.
It's fairly common to combine the two bands and use just one network name (SSID) for both 2.4 and 5GHz. This has advantages and disadvantages. For a start, if combined, it's not possible to force your laptop to only use the 5GHz band, so it's worth splitting them out into two separate Wi-Fi networks if your router offers this option. Newer BT Home Hubs have the setting:
When you have separate networks, you can rename them (with 5GHz at the end of the 5GHz one, say) so you can easily identify each network from your laptop, phone or tablet and know which one you're connected to.
Does my laptop support 5GHz Wi-Fi?
The best way to find out is to open Control Panel - search for it in the Windows search box - then go to Device Manager and find the make and model of your laptop's Wi-Fi under the Network adapters section.
This laptop, for example, has a Qualcomm Atheros AR9285 adaptor. Searching online for this make and model brings up plenty of results for its specifications which show that it works only on 2.4GHz. If your adapter supports 802.11ac, it will definitely support 5GHz. In most cases, 802.11n adapters will also support 5GHz.
You can also right-click on the adapter in Device Manager, click Properties and then switch to the Advanced tab. You'll see a list of properties, one of which should mention 5GHz. If you don't see an option to enable or disable 5GHz, either your adapter doesn't support it, or the wrong drivers are installed.
And if you do find that your laptop doesn't have 5GHz Wi-Fi, you can easily add it by buying a USB Wi-Fi dongle for your laptop. These are inexpensive - around £10-30 / $10-30 - and mean you can upgrade your laptop's Wi-Fi without opening it up. We've rounded up the best USB Wi-Fi adapters.
How to connect to 5GHz Wi-Fi from your laptop
This is the easy part. If you can see your router's 5GHz wireless network name in the list of available Wi-Fi networks, you can click on it and then click 'Connect'. Enter the password and that's it.
In the image above you can see the two separate networks broadcast from a BT Home Hub 5. Click on the Wi-Fi icon (highlighted) to see the wireless networks in range.