Is your WiFi slower than usual? Have you noticed lag when playing online games, or that streaming your favorite Netflix series keeps stopping, especially at night? You’ve probably suspected that your internet provider is simply failing.
However, there is another very common reason for this slowdown: someone is using your network without permission (commonly known as piggybacking or intrusion). Not only is this frustrating, as it prevents you from watching your The Office marathon in peace, but it also poses a serious risk to your security and the privacy of your personal data. The good news is that you don’t need to be a computer expert to detect the thief. There’s a very simple trick right in front of you: your router’s lights.
The Light Test
Just like the white smoke at the Vatican every time a new Pope is elected, your router has several lights that indicate its status. We are particularly interested in one in particular: the “Activity,” “WLAN,” or “WiFi” light, which flashes whenever there is data traffic on your wireless network.
To begin the experiment, start by disconnecting or turning off all devices that use Wi-Fi in your home. If you are unlucky enough to have appliances connected to the Internet, disconnect them from the network as well. (If even voice-activated dishwashers have the option of connecting to Wi-Fi to turn on the program remotely, don’t ask us why.)
As we were saying, turn off all cell phones, tablets, Smart TVs, consoles, and any other connected devices. Now watch the activity light on your router for a few minutes. If the light continues to flash constantly or intermittently, it means that an unknown device is connected and using your bandwidth.
However, this technique has a limitation, as there are smart appliances—such as security cameras, speakers, or voice systems—that connect and send small packets of data automatically, even when you’re not using them. Therefore, the light may flash even if there is no active intruder, making this method only a first warning sign, but not a completely definitive confirmation.
Other Definitive Methods for Hunting Intruders
You’ve kept an eye out and have your suspicions, so we can move on to the next step: analyzing the router interface. This is the most reliable definitive method for verifying all users. To do this, you must access your router’s “control panel” through your web browser.
Open your browser and enter the default gateway IP address, which is usually 192.168.1.1 or 192.168.0.1. From there, you will be asked to enter an administrator username and password. Then you have to go to the “connected devices” section. There you will see a list of all the devices connected to the Wi-Fi network. If you see a device name that you don’t recognize, you have confirmation that there is an intruder.
If you are one of those users who prefer system tools, there is a method built into Windows and Mac. To do this, open the command line or terminal. Type the command “arp -a” and press Enter. Here you will also see a technical list of IP and MAC addresses that your computer has recently interacted with on the local network.
Why is it dangerous to have your WiFi stolen?
Although many people are only bothered by the loss of speed, the real problem with an intruder on your Wi-Fi is security. If someone has been able to sneak into your Wi-Fi network, it means they have already crossed your first line of defense. If this person or individual carries out any illegal activity from your IP (such as downloading prohibited material or launching cyberattacks), the police authorities will trace their crime back to your IP address. This makes you initially responsible until proven otherwise.
Furthermore, once inside your Wi-Fi network, the individual is able to attempt to access shared resources. If you have any networked hard drives, unprotected files, or printers, they will be able to interact with them. They can also perform “Man-in-the-Middle” attacks to try to spy on unencrypted data traffic from the websites you visit. To prevent someone from sneaking onto your Wi-Fi network, the best security standard is WPA3-Personal.