Found an unknown device on your Wi-Fi? What to do

An unknown device on Wi-Fi at home is most often something you own and forgot about, like a smart plug, a TV box or a phone using a private address. Identify it first by its maker and by switching things off. If you still cannot explain it, change your Wi-Fi password and tighten your router settings, which removes anyone who should not be there.

Do not panic: most unknown devices are yours

Homes collect connected gadgets quietly. A few that often show up as a mystery:

• Smart plugs, bulbs and light strips.
• Smart speakers and displays.
• The TV, its streaming stick and the soundbar.
• Printers, which often join Wi-Fi out of the box.
• Robot vacuums, air purifiers, washing machines and fridges.
• Doorbells, cameras and thermostats.
• A visitor's phone from last weekend that still remembers your password.
• Your own phone, if it uses a private, random MAC address.

Many of these report no friendly name, so they appear as just an address and perhaps a maker. That looks alarming but is usually harmless.

How to identify an unknown device on Wi-Fi

1. Write down what you see. Note the device's IP address, MAC address, maker and any name. If you are not sure where to find this, see how to see who is connected to your Wi-Fi.
2. Look up the maker. The first half of a MAC address points to the company that made the network chip. A chip maker is not always the product brand, but it narrows things down.
3. Check the name for clues. Names like "ESP" followed by numbers often belong to small smart-home gadgets. Names with a model number often belong to TVs or printers.
4. Switch things off one by one. Turn off a suspected device, wait a minute and scan again. If the entry vanishes, you found it.
5. Ask the household. Someone may have plugged in a new gadget or given the password to a friend.
6. Check when it was first seen. Some routers show how long a device has been connected. A device that appeared the day you bought a new lamp is probably the lamp.

What if you still cannot explain it?

If the device does not disappear when you switch your own things off, treat it as unwanted. Act calmly and in this order:

1. Change the Wi-Fi password. This is the single most effective step. Every device has to rejoin with the new password, and anyone who should not be there is locked out.
2. Use strong encryption. In the router settings, choose WPA3 if all your devices support it, or WPA2 with AES. Avoid WEP and "open".
3. Turn off WPS. WPS lets devices join with a button or PIN, and the PIN method has known weaknesses.
4. Change the router's admin password. The admin login controls everything. If it is still the default, change it now.
5. Update the router firmware. Updates fix security holes.
6. Block the device if your router allows it. Many routers can block a MAC address. This is a useful extra, but a determined person can change their MAC, so the password change matters more.

Our full list of steps to secure your home Wi-Fi goes into each of these in more detail.

Why not just block it and move on?

Blocking one device treats the symptom. If someone got in, they know your password, and they can join again with a different device or a new MAC address. Changing the password closes the door for everyone at once. It is a small hassle to reconnect your own devices, but it is the reliable fix.

What to do after the clean-up

• Store the new password safely, so you are not tempted to pick something weak. Our guide on where to keep Wi-Fi passwords has a few good options.
• Put visitors on a guest network if your router has one. That keeps them away from your own devices.
• Rename devices in the router where you can, so the next check is quick.
• Check again in a week to make sure the mystery device has not come back.

Could it be a neighbour?

It can be, especially if your password was simple, was shared at some point, or is still the default printed on the router. A neighbour showing up as an unknown device on Wi-Fi may slow your connection and could see other devices on your network. The same fix applies: a new, strong password, modern encryption and WPS off.

How CellRadar helps

CellRadar has a Device Scanner that shows the devices on your Wi-Fi with names and makers, and a MAC lookup tool for nameless entries. Network Guard can alert you if a new device joins later. The Network Health Report gives a score out of 100 with security findings, so you can see what to tighten next.

Frequently asked questions

Can an unknown device on my Wi-Fi see my files?

It can see other devices on the same network, and could reach any shared folders or services left open. That is why it is worth changing your password and turning off sharing you do not use.

Will changing my Wi-Fi password kick everyone off?

Yes, every device disconnects and has to rejoin with the new password. That includes your own phones, TV and smart devices, so plan a few minutes to reconnect them.

Is MAC filtering enough to keep people out?

Not on its own. A MAC address can be copied or changed, so filtering is a small extra layer. A strong password with WPA2 or WPA3 is the real protection.

Why does the same unknown device keep coming back?

If it comes back after a password change, it is most likely one of your own devices rejoining. Turn your gadgets off one at a time and scan again to find it.