Quick answer: The clearest sign someone is using your Wi-Fi without permission is unexplained slowdowns, particularly at times when your own devices should be idle. To confirm it, check your router’s connected devices list, either through the manufacturer’s app or by logging into the router’s admin panel directly, and look for any device you do not recognise.
A Wi-Fi network is easy to set up once and never think about again. But an unexplained slowdown, especially one that does not match your own household’s usage, is often the first real clue that someone else has quietly attached themselves to your connection. Here is how to check properly and remove them.
The Warning Signs Worth Noticing
A few patterns consistently show up when an unauthorised device is on your network:
- Unexplained slowness, particularly during off-peak hours. If your connection lags when your own devices should not be placing much demand on the network, particularly during video calls or online gaming, that timing mismatch is a meaningful clue.
- A sudden spike in data usage that does not match your household’s normal habits, especially if you are on a capped or metered plan.
- Frequent interruptions or unexpected disconnections, even for devices that usually maintain a stable connection.
- Router activity lights blinking steadily even when none of your own devices are actively using the internet.
None of these alone is proof, ordinary background updates and smart home devices can also cause fluctuations, but a pattern that persists and does not match your actual usage is worth investigating properly.
Check Your Router’s Connected Devices List
This is the definitive check. Most modern routers, including TP-Link Deco, Google Nest, and Amazon eero, come with a companion app that shows every device currently connected to your network.
- Open your router’s app and look for a section labelled “Connected Devices,” “Clients,” or similar.
- Review the full list. Each entry typically shows a device name, manufacturer, and sometimes the MAC address, making it easier to identify your own smart TV, laptop, or phone versus something unfamiliar.
- Flag anything you do not recognise. Some entries may look unfamiliar simply because of generic manufacturer naming, so cross-check against your own known devices before assuming the worst.
No Router App? Log In to the Admin Panel Directly
If your router does not have a dedicated app, you can check the same information through its web-based admin interface:
- Find your router’s IP address, commonly 192.168.1.1 or 192.168.0.1, sometimes printed on a sticker on the router itself.
- Type that IP address into a browser’s address bar while connected to your Wi-Fi network.
- Log in using your router’s admin credentials, also often printed on the device unless you have changed them.
- Find the section labelled “DHCP Client List,” “Connected Devices,” or “Attached Devices.” Every device currently using your network will be listed here.
A Simple Low-Tech Confirmation Test
If you want additional confidence before acting, turn off every device you own that connects to Wi-Fi, phones, laptops, smart TVs, smart home devices, everything. Then check your router’s activity lights or connected devices list again. If regular data activity is still visible with nothing of yours powered on, that is a strong confirmation that an unauthorised device is on your network.
How to Remove an Unauthorised User
Two approaches work, depending on how surgical you want to be:
The Fast, Blanket Fix: Change Your Wi-Fi Password
Changing your network password immediately disconnects every device, including the unauthorised one, since all devices need the new password to reconnect. This is the simplest fix, though it does mean reconnecting all of your own devices afterwards.
The Targeted Fix: Block by MAC Address
If you want to remove a specific device without disrupting everyone else, find its MAC address in your connected devices list, then look for a setting called “MAC address filtering” or “MAC blocking” in your router’s admin panel. Blocking a device by its MAC address prevents that specific device from reconnecting, even if it still knows your password.
Secure Your Network Going Forward
- Use WPA3 encryption if your router supports it, or WPA2 at minimum. Older WEP encryption is significantly easier to compromise and should be avoided entirely.
- Set a strong, unique Wi-Fi password, and avoid reusing the default password printed on the router, since these can sometimes be guessed or found through the router’s model number.
- Disable WPS (Wi-Fi Protected Setup) if you do not actively use it, since it has known vulnerabilities that can allow unauthorised access.
- Set up a separate guest network for visitors, keeping your main network reserved for devices you trust.
- Keep your router’s firmware updated, closing known security vulnerabilities as they are discovered.
Common Questions
Will changing my Wi-Fi password definitely remove an unauthorised user?
Yes, changing the password disconnects every device from the network, including the unauthorised one, since all devices must reconnect using the new password.
How can I check who’s on my Wi-Fi without downloading an app?
Log into your router’s admin panel directly by typing its IP address, commonly 192.168.1.1, into a browser while connected to your network, then look for the connected devices or DHCP client list.
Is a neighbour using my Wi-Fi actually a security risk?
Beyond slowing your connection, anyone with access to your network can potentially see and interact with other devices connected to the same network, which is a genuine privacy and security concern, not just a bandwidth issue.
What is MAC address filtering?
A router setting that lets you block a specific device from connecting to your network using its unique hardware identifier, even if that device still has your Wi-Fi password.
Should I use WPA2 or WPA3 for my Wi-Fi security?
WPA3 if your router and devices support it, since it offers stronger protection. WPA2 is an acceptable minimum. Avoid older WEP encryption entirely, as it is significantly easier to compromise.
The Bottom Line
Unexplained slowdowns, unusual data spikes, and router activity when your own devices are idle are the clearest signs someone else may be on your Wi-Fi. Checking your router’s connected devices list, either through a companion app or its admin panel directly, gives a definitive answer. From there, changing your password or blocking the specific device by MAC address removes the problem, and enabling WPA3 encryption with a strong, unique password keeps it from happening again.