Short answer: open your router’s app or log in to its web page and look for the list of connected or attached devices. If you see something you don’t recognise and can’t account for, change your Wi-Fi password. Every device then has to rejoin, and anyone who shouldn’t be there is out.

Find the list

Every router keeps one, though names vary: Attached Devices, Clients, Device Manager or Network Map. On NETGEAR routers, for example, the Attached Devices page lists wired and wireless devices separately, with each one’s status, name, IP address and MAC address. In the Nighthawk app, Device Manager shows the same list with each device’s connection type (wired, 2.4 GHz or 5 GHz) and whether it’s online.

If you’ve never logged in, see how to log in to your router.

Read the list

  • Name: often the device’s own name (“Living-Room-TV”), sometimes just a manufacturer or blank.
  • Connection type: wired devices are physically plugged in, so they’re rarely intruders.
  • MAC address: NETGEAR notes that a device’s IP address can change when it rejoins the network, while its MAC address doesn’t. That makes the MAC the better way to recognise a device over time.

Unknown devices are usually yours

Phones and laptops often use a random MAC address for privacy. The Wi-Fi Alliance describes this randomization, including using a different random address on different networks. So a nameless device with an unfamiliar address is often your own phone, a smart plug or a TV.

Remove someone

Many routers let you block a device, but blocking one address won’t stop someone who knows your password from reconnecting with another device. The reliable fix is to change the Wi-Fi password: devices have to reconnect with the new one. See how to change your Wi-Fi password.

To keep visitors and smart devices away from your computers in future, set up a guest or IoT network, and check the rest of our router security checklist.