How to See Who Uses Your Wi-Fi and Block Access

Is Someone Using Your Wi-Fi Without Your Knowledge?

Your internet suddenly got slower, the router is blinking more than usual, and you haven’t downloaded anything heavy in recent days. This combination of symptoms almost always points to the same culprit: someone is using your network without your permission. It could be a neighbor who discovered your password, an old forgotten device still connected, or even a family member’s device consuming bandwidth in the background without anyone noticing.

The good news is that checking who’s on your network and blocking unwanted access doesn’t require you to be an IT technician. With your router’s admin panel or a few free applications, you can get a complete view of all connected devices and take necessary action in minutes.

This guide covers everything from the most basic method, directly through the router, to third-party tools for those who want more control. What you’ll need: access to the router (the physical device and admin credentials), a computer or phone connected to the same network, and about 15 minutes.

What You Need Before Getting Started

Before any step, gather basic information about your network. You’ll need the gateway IP address (your router’s address on the local network), which is typically 192.168.0.1 or 192.168.1.1 for most routers sold in Brazil. You’ll also need the admin panel login and password, usually printed on a sticker on the bottom or side of the device.

If never changed, the default login is usually something like admin/admin or admin/password. Check your specific model’s manual to confirm. Also note the names of your own devices, as you’ll need to identify what’s yours and what’s unfamiliar in the connection list.

How to See All Connected Devices Via Router

This method works for any router, regardless of brand.

Open a web browser (Chrome, Firefox, Edge) on a computer or phone connected to your network.
Type your router’s IP address in the address bar. Try 192.168.0.1 first; if that doesn’t work, try 192.168.1.1.
Enter your admin username and password when prompted.
Look for a section called “Connected Devices”, “DHCP Clients”, “Network Map”, or “Connected Devices”. The name varies by manufacturer’s interface.
You’ll see a list with each device’s name, its MAC address (a unique hardware identifier, like a device’s fingerprint), and the local IP address assigned to it.
Compare this list with your devices. Smartphones, notebooks, smart TVs, gaming consoles, and smart home devices should appear with recognizable names.

Unknown devices frequently appear with generic names like “android-xxxxxxx”, “unknown”, or just the MAC address without identification. These are the candidates to investigate.

Identifying Suspicious Devices by MAC Address

The MAC address consists of six pairs of hexadecimal characters, like A4:C3:F0:12:34:56. The first three pairs identify the manufacturer of the network hardware. You can search any MAC address in the IEEE (Institute of Electrical and Electronics Engineers) public database to discover the manufacturer and get a clue about the device type. If “Xiaomi”, “Apple”, or “Samsung” appears, you can narrow down your search among your own devices.

How to Block an Unwanted Device

After identifying the intruder, there are two main ways to block it.

MAC Address Blocking (MAC Filtering)

MAC filtering prevents a specific device from connecting to your network, even if it knows your Wi-Fi password.

In your router’s panel, look for sections called “Access Control”, “MAC Filter”, or “Wireless MAC Filtering”.
Enable blacklist mode or whitelist mode. Blacklist blocks the listed addresses; whitelist only allows listed addresses.
To block a specific device, use blacklist and add the intruder’s MAC address.
Save settings and restart the router if necessary.

MAC filtering is an additional security layer, but it’s not foolproof. More experienced users can spoof the MAC address (a technique called MAC spoofing) to bypass the block. Use this measure alongside others, not as your only defense.

Changing Your Wi-Fi Password (The Most Effective Method)

If you suspect someone simply obtained your password, changing your Wi-Fi password is the most direct and complete solution.

In your router’s panel, go to “Wireless Settings” or “Wi-Fi”.
Find the password field (usually called “WPA Key”, “Passphrase”, or “Security Password”).
Replace it with a strong password: at least 12 characters, with uppercase letters, lowercase letters, numbers, and symbols.
Save. All devices will be disconnected and will need to enter the new password, including yours.

Take the opportunity to check if the security protocol is set to WPA3 or at least WPA2-AES. Older protocols like WEP and WPA-TKIP are considered insecure and easy to break.

Third-Party Tools to Monitor Your Network

For those wanting more convenience and a more visual interface, there are applications that scan your network and list connected devices more clearly than many router panels.

Fing (Android and iOS, free with optional paid features): one of the most popular apps for this purpose. It scans the local network, lists all devices with name, manufacturer, IP, and MAC, and can alert you when a new device connects. Available in official app stores.
Advanced IP Scanner (Windows, free): desktop software that performs complete local network scans. Widely used by network administrators but accessible for regular users.
LanScan (macOS, free with paid version): Mac equivalent with similar functionality.

These applications don’t replace router settings, but they’re great for getting a quick overview without needing to access the admin panel every time.

Router Settings That Increase Network Security

Identifying and blocking intruders is a reaction. The ideal is to create barriers so it doesn’t happen again. Some settings deserve immediate attention in your router’s panel.

Change your router’s admin password: most people never do this. A weak admin password is an open door for anyone on the local network.
Disable WPS (Wi-Fi Protected Setup): this feature was created to simplify connections via physical button or PIN, but has known vulnerabilities that allow brute-force attacks.
Enable guest network: create a separate network for visitors and IoT devices (like cameras, smart lights, and voice assistants). This way, these devices stay isolated from your main network, where your notebook and phone are.
Check if firmware is updated: manufacturers regularly release security updates. In your router’s panel, look for the firmware update option in the advanced settings section.

If you’re experiencing coverage issues beyond security and are thinking of expanding your network to other floors or rooms, this comprehensive guide on how to improve Wi-Fi signal in two-story homes can be a good complement to this tutorial.

Common Issues and How to Solve Them

I can’t access the router panel via the default IP Open the command prompt (Windows) or terminal (Mac/Linux) and type ipconfig (Windows) or ifconfig (Mac/Linux). The Default Gateway address is your router’s IP. If it still won’t open, try connecting your computer to the router via network cable directly.

I forgot the admin password If the password was changed and you don’t remember it, the only way out is to perform a factory reset of the router. Usually there’s a small reset button on the back of the device; hold it for 10 to 15 seconds until the lights blink. Warning: this erases all settings, and you’ll need to reconfigure your network from scratch.

Devices keep reappearing after MAC blocking Most likely the device is using MAC randomization, a feature in recent versions of Android and iOS that automatically changes the MAC address to preserve privacy. In this case, changing your Wi-Fi password is the most effective solution.

The app shows more devices than I expected Don’t worry. Each device connected to the network occupies an entry in the list. A modern smartphone may appear twice if it’s connected to both the 2.4 GHz and 5 GHz Wi-Fi bands separately. Notebooks with network cable and Wi-Fi enabled simultaneously also generate two entries. Count carefully before concluding there’s an intruder.

Frequently Asked Questions About Wi-Fi Monitoring and Blocking

Is MAC filter blocking permanent?

Yes, as long as the setting remains active on your router. But if the blocked device changes its MAC address (via randomization or manually), it may reconnect. That’s why combine MAC filtering with password changes for better security.

Can my Internet Service Provider (ISP) see who uses my Wi-Fi?

Your provider has access to traffic leaving your network to the internet, but can’t directly see the list of devices connected to your local router. This management is done exclusively on your router’s panel.

Can I limit a specific device’s speed without completely blocking it?

Yes, as long as your router supports QoS (Quality of Service). This feature allows you to set bandwidth limits per device. Mid-range and advanced routers usually have this option, but basic models provided by ISPs typically don’t. Check your device’s technical specifications.

Do operator routers (Vivo, Claro, TIM, etc.) have these functions?

Partially. Most routers provided by Brazilian operators have a simplified panel with device list and blocking options. Advanced features like detailed QoS and complex filters are usually absent or blocked. If you want more control, investing in your own Anatel-approved router is the natural path.

Keep Your Network Under Control as a Routine

Checking who’s on your network doesn’t need to be an emergency task. With Fing or any similar scanner, you can do this check monthly in less than two minutes. Changing your Wi-Fi password every six to twelve months is good practice, especially if you tend to share it with visitors.

Home network security is one of the areas where small actions have big impact. Disabling WPS, keeping firmware updated, and using a strong password on your admin panel already put you ahead of most home users. And when that inexplicable slowdown happens, now you know exactly where to start investigating.