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ZDNET’s key takeaways
- Wi-Fi slowing down, or unfamiliar devices on your network? You may have an intruder.
- There are various ways to quietly confirm your suspicions.
- Here’s how to verify whether someone is using your Wi-Fi and how to stop it.
Monitoring is becoming an ever-present part of daily life. Facial recognition cameras are scattered across public spaces; our online activity is constantly tracked, and it’s uncommon to go to a social gathering without someone pulling out their phone to record.
Yet the thought of that kind of monitoring invading our own homes can be even more unsettling. Have you spotted an unknown device linked to your home network? Or has your internet speed been dropping noticeably? If an unauthorized person is piggybacking on your Wi-Fi, that’s a major breach of your privacy — and it’s also unjust, since you’re the one footing the bill for that service.
Also: Your home Wi-Fi isn’t nearly as private as it should be — 6 free ways to lock it down
When someone gains access to your Wi-Fi, they’re not just siphoning off the bandwidth you pay for — they can also compromise your privacy and security, harvest your data, and potentially even link you to illicit online behavior carried out by someone else.
The good news is that spotting uninvited users on your network and removing them can be surprisingly simple. Here’s how to identify them, kick them off, and prevent them from coming back. Watch for these three red flags.
1. Your internet feels sluggish
There are plenty of explanations for why your internet connection might suddenly shift from fast to frustratingly slow, or why you might experience random drops and delays.
Common, legitimate causes for internet disruptions include defective router hardware, damaged external cables, poor signal strength, or problems with your internet service provider (ISP), such as area-wide outages. On the software side, choosing the wrong VPN or VPN server to secure your connection can also cause significant speed reductions.
Also: Best VPN services: Expert tested and recommended
That said, a sluggish connection can also stem from unwelcome guests on your network who are hogging your bandwidth. The more devices connected to a Wi-Fi access point, the greater the traffic load. This is particularly noticeable when someone is streaming in high definition, gaming online, or downloading large files via torrents.
Distinguishing between legitimate causes of slowdowns and latency caused by a bandwidth thief can be tricky. Start by checking your ISP’s service status page for known issues, visit downforeveryoneorjustme.com to see if online services are experiencing outages, and inspect your hardware — including cables and connectors, since loose wiring can also cause broadband problems.
2. Unknown or unrecognized devices on your network
Anyone using your Wi-Fi without your consent will need to connect a device — whether it’s a smartphone, computer, smart speaker, or smart home gadget.
You might also notice sluggish speeds and heavy traffic loads, videos constantly buffering, and even your own devices dropping off the network unexpectedly as the system struggles under the weight of too many devices — authorized or not — competing for the same bandwidth.
Also: Should you switch to a Wi-Fi 7 mesh router? My home testing reveals what got better (and what didn’t)
Another clue could be the activity indicators on your router. For instance, blinking lights on your hardware might signal network traffic when you aren’t expecting any. Still, consult your router’s manual for other possible explanations before jumping to the conclusion that unknown devices are the culprit.
3. Router stops working, or you lose Wi-Fi access
If your Wi-Fi abruptly cuts out, it could indicate that someone is tampering with your setup behind your back. It becomes even more suspicious if your network drops and reconnects at predictable times — say, whenever you start streaming music.
To keep tapping into your Wi-Fi hotspot, the person needs to be within range — and if you have a strained relationship with a neighbor or someone else in your household, there’s always a chance they’re intentionally disrupting your connection. For instance, if someone has gained access to your Wi-Fi and its admin panel, they can sever your connection whenever they want.
Also: How I turned my old Android phone into a Wi-Fi extender — and fixed dead spots at home
Additionally, if your Wi-Fi password has been changed and you’ve been locked out, someone has likely taken control and reset it without your knowledge.
Keep in mind, though, that hardware malfunctions could be the real issue rather than a malicious actor. Routers degrade over time, ISPs sometimes deliver unreliable service, and even weather conditions can affect your connectivity. However, if there’s a recurring pattern in the outages — for instance, at the same time every day — it may be intentional.
How can someone use my Wi-Fi without permission?
The simplest explanation is usually the correct one, and with Wi-Fi, it almost always comes down to your password.
A weak, easily guessable password could be the culprit, or one that was shared without your consent. It’s also possible for attackers to launch brute-force or dictionary attacks against certain Wi-Fi networks — running software that systematically tests combinations of letters, numbers, phrases, and special characters to crack the password and gain entry.
There’s also the matter of Wi-Fi security protocols themselves. The main standards are WPA, WPA2, and WPA3. You can check which protocol your Wi-Fi uses by navigating to your router’s wireless settings: on macOS, hold the Option key and click your Wi-Fi icon; on Windows, go to Settings, then Wi-Fi, and then the Security tab.
The newer the standard, the harder it is for attackers to break in — but if passwords are weak or the network is misconfigured, intrusion is still entirely possible regardless of the protocol.
Outdated router firmware can also leave your Wi-Fi exposed, as it may contain security holes that can be exploited. You can check your hardware’s firmware version through the router’s admin panel to see whether it updates automatically or requires a manual update via the web interface.
Also: How to update your router’s firmware (and why you should be doing it regularly)
How can I find suspicious devices on my network?
The most straightforward way to confirm your suspicion that someone is on your Wi-Fi without authorization is to run a network scan.
The first step is to access your router’s admin panel through a web browser. Your router manufacturer or ISP should provide the address you need to enter; if you’re unsure, try 192.168.0.1 or 192.168.1.1. Another option is to open your phone’s Wi-Fi settings, tap your home network, go to Settings, and select “Manage router” if the option is available — this should take you directly to the admin panel.
Also: I used this free tool to see what data the internet has on me — and the results were disturbing
When you navigate to the admin panel in your browser, you may see a warning that the connection isn’t secure, and you’ll need to log in with your router or hub password. Once you’re in, depending on your ISP, you may be able to view a complete list of all devices currently on your network.
Alternatively, you can use a dedicated network scanner tool to discover and display all devices and IP addresses connected to your network, then look for anything you don’t recognize. Network scanner options include
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Tools like Fing, Nmap, and WiFi Analyzer can help you monitor your network.
How else can I detect unauthorized Wi-Fi users?
- Test your internet speed: Run speed tests at various times throughout the day to identify unusual patterns. For instance, if your connection slows down significantly every evening when a neighbor starts streaming 4K content, that could explain the drop in performance—or even complete loss of connectivity.
- Review connection logs: Tech-savvy users can use network scanning tools like Nmap or Fing to generate detailed logs showing which devices are connected, how long they’ve been active, and when they typically join the network.
- Observe your surroundings: Pay attention to environmental clues. If a neighbor’s loud music cuts out the moment you reboot your router, it might indicate they were piggybacking on your Wi-Fi.
Also: Your smart home could be vulnerable—here are 6 expert-recommended ways to safeguard your devices from cyberattacks
How can I block unwanted users from my network?
- Update your Wi-Fi password: If someone has guessed or obtained your current password, changing it immediately will disconnect all unauthorized users. Access your router’s admin interface (as explained earlier) to make this change.
- Create a stronger password: Avoid using default credentials or simple, memorable phrases—even for guest access. Opt for a complex combination of letters, numbers, and symbols. While it’s inconvenient, remember to reconnect all your own devices afterward, since the old password will no longer work. Unlike sensitive online accounts, writing down your home Wi-Fi password and storing it securely at home poses minimal risk.
- Secure your router’s admin login: Ensure your router’s administrator username and password aren’t set to common defaults like “admin/admin.” Replace them with a strong, unique combination and keep them in a safe place.
- Upgrade your Wi-Fi security protocol: Outdated standards like WPA are highly vulnerable. Switch to a modern encryption method—ideally WPA3—via your router’s settings under “Security” or “Wireless.” You’ll likely need to set a new password and reconnect your devices after making this change.
- Set up a guest network: When sharing Wi-Fi access, create a dedicated guest network. This isolates visitors from your primary network, giving you control over their access duration, bandwidth usage, and device visibility.
