If you’re reading this and wondering how you’d even know if an ‘unknown’ device is connecting to your Wi-Fi, the answer lies in your internet router or whichever device provides you with Wi-Fi.
In most cases that is your broadband router, but it could also be a mesh Wi-Fi system, a Wi-Fi extender or booster.
Whatever your setup, you need to log into the device that supplies your Wi-Fi and have a look in its menus to find a list of connected devices.
Simply logging in to a router can be a challenge, which is why we’ve provided a step-by-step guide. Essentially, though, you need to know the IP address of the router which you should be able to get from any device connected to it, such as your laptop or phone.
Once you have that address, enter it into your web browser’s address bar – the top one, not the Google search box which appears lower down the page. An example of a router’s IP address is 192.168.0.1 and you’d type it in just like that with nothing else.
Press Enter and, assuming you have the correct address, you’ll see your router’s web page. I have a BT Smart Hub, so can see the list of connected devices on the home page without having to log in.
When you’re looking through the list, bear in mind that it works like a visitor’s book: many of the devices will have connected in the past, but not be connected right now.
You’ll probably see a lot of unknown devices because the friendly name (such as Jim’s iPhone) either doesn’t exist or isn’t picked up by your router.
What you’ll see instead is its IP address and MAC address, plus a ‘name’ which may or may not contain any hints as to what the device is.
This is what unknown means: the device won’t necessarily be called ‘unknown’ but you won’t be able to identify what it is.
As you can see from this image, some of the friendly names are simply IP addresses, which isn’t helpful. The ones beginning ‘amazon-‘ are more helpful, but could be any Amazon device: an Echo, Fire tablet or Fire TV.
How to identify an unknown device on your network
The names in the list can help you narrow it down, and some routers – my Smart Hub included – allow you to filter the list by only those that are currently connected.
Even if you only have a handful of Wi-Fi devices, that list will be populated by your old devices that you may have upgraded, or friends’ devices which you’ve allowed to connect when they were visiting, so it’s worth looking for this option so you can find unknown devices that are connected right now.
The chances of a neighbour or even someone malicious being connected to your Wi-Fi are extremely slim, unless you don’t have a password for it. As standard, all routers have a unique Wi-Fi password these days, and it’s virtually impossible to hack.
It means your unknown devices are probably gadgets you’ve forgotten about, such as your DVR (maybe a Freeview or Sky box), a smart thermostat, plug or another smart home gadget.
The way to identify them will depend upon whether they have a screen or not. Phones, tablets, PCs and laptops all offer easy access to their IP address. Just go to their network settings and hunt around until you find it.
Note that the IP address is usually handed out by your router and isn’t fixed to a particular device (unless you tell your router to always use that address – this is known as a static IP address).
But this is where the MAC address comes in useful: this is unique to the device in question.
The MAC address is often printed on a sticker on the gadget itself and is the best way to work out which device is which. It is six pairs of hexadecimal numbers, such as 00:40:96:B1:C0:8E.
Most usefully, the first six of these identify the manufacturer, so you can use a website such as MAClookup.app to find out who makes the device that you’re trying to identify.
This should narrow your search considerably. And once you have identified what it is, you should find your router lets you change the friendly name of a device (on the Smart Hub double click on the product in the list, then type in the 'Device name:' box) so you know what it is next time you view the list.
It might also allow you to associate an icon with it so you can see at a glance what’s a phone, what’s a tablet, what’s a PC and what’s a smart gadget.
If you can’t find out the device’s MAC address or IP address, then one option is to unplug it from the mains (or remove the batteries) and see if you can identify what disappears from the list of connected devices in your router – you may have to refresh the list for it to disappear.
What to do if you can’t identify a device connected to your Wi-Fi
The simplest way to prevent it using your Wi-Fi is to change your router’s Wi-Fi password. This means you’ll have to enter the new password for all your own devices, which is a pain.
Most routers have the option to do MAC address filtering. When enabled, this becomes a list of devices which are allowed to connect to the router. It means you need to enter the MAC address of all your devices, which is also a pain, unless your router happens to have the option to block specific MAC addresses, which would save a lot of hassle.