Is someone using my WiFi? How to check and protect your PC

Slow internet, a light on the router that blinks when all your devices are off, a device name you don't know. Here is how to find out who is really on your WiFi, how to lock out anyone who shouldn't be, and how to keep your Windows PC safe even on a network you share.

1. Signs, and what they really mean

• Slow internet in the evening: often just a busy provider, a video stream or an update on another of your devices. Not proof of a stranger.
• The WiFi light keeps blinking with all your devices off: a better sign. Remember smart TVs, speakers, plugs, game consoles and phones in standby also use the WiFi.
• A device name you don't recognise: worth checking in the router, as below. Many devices have odd names such as ESP_3A2F1C (often a smart plug or light) or a random-looking phone name.

2. See every device on your WiFi: the router's list

Your Windows PC only sees its own connection. The router (the box from your internet provider) hands out the addresses on your network, so it is the one place that knows every device.

1. Open the router's page: the address and login are usually on a sticker on the router, often 192.168.0.1, 192.168.1.1 or a name such as fritz.box. Many providers also have a phone app for their router.
2. Find the device list: it is called something like Connected devices, Attached devices, Home network or DHCP clients. (DHCP is simply the part of the router that gives each device its address.)
3. Go through the list: each line has a name, an address and often a MAC address, the fixed hardware number of a device's network card. On a phone or PC you can look up its own MAC address to match it. Note: newer phones use a different, random MAC address for each WiFi, so compare the one shown in the phone's WiFi settings for your network.
4. The switch-off test: switch off WiFi on all your devices you can think of, then refresh the list. What is still connected is either a device you forgot or someone else.

Many routers can also block a single device from this list. That helps for the moment, but a new password (next step) is what really locks someone out.

3. Lock out anyone who shouldn't be on it

1. Set a new WiFi password: long is better than complicated, for example four or five unrelated words. Every device then has to reconnect with the new password, so only the people you give it to are back on.
2. Use WPA2 or WPA3 encryption: this is the setting that scrambles your WiFi traffic and requires the password. In the router's WiFi or security settings choose WPA3, or WPA2/WPA3 if older devices need it, or at least WPA2 (AES). Never "open", WEP or WPA alone: they can be broken quickly.
3. Switch off WPS: WPS is the "connect at the push of a button or PIN" feature. The PIN version in particular can be guessed. You can still connect devices with the password.
4. Change the router's admin password: this is the password for the router's own settings page, not the WiFi password. Many routers come with a default one that anyone can look up. Change it, so nobody on your WiFi can change your router.
5. Update the router's firmware: firmware is the router's own built-in software. Look for Update or Firmware in its settings, or switch on automatic updates. Routers your provider no longer updates are worth replacing.
6. Use a guest network for visitors and, if your router has one, for smart home devices. Guests then get internet, but not your own devices.

4. Protect your PC on a shared network

You can't always control the network: a flat share, a hotel, a café, student housing. Even at home, a smart device could be badly made. So the PC itself should not trust the network more than it has to.

Set the network to Public

Windows has network profiles: a setting that tells Windows how much to trust a network. Private is for a home network you trust: your PC can be found by other devices, and file and printer sharing can work. Public is for everything else: your PC is hidden from other devices, and the Windows Firewall is stricter.

• Windows 11: Settings › Network & internet › Wi-Fi › your network's properties › Network profile type › Public network.
• Windows 10: Settings › Network & Internet › Wi-Fi › click your network › Network profile › Public.

If you don't share files or printers between your own computers, Public is the safer choice even at home.

More simple steps

• Keep the Windows Firewall on for all networks (Windows Security › Firewall & network protection: all should say "Firewall is on").
• Install Windows updates and use a password or PIN to sign in.
• Look for the padlock in the browser: with https://, others on the WiFi can see which site you visit, but not what you send or read.

5. Is my PC reachable from the internet, too?

WiFi is only the local side. The other side is your router's connection to the internet. If the router forwards a port to your PC (for example for remote access, a game or a camera), anyone on the internet can try that door. You can check it with our free online port check, which looks at your own address only.

6. Watch your PC's side of the network with Coinetic

Doing this by hand means...

• the router shows who is on the WiFi, but not who tries to reach your PC;
• Windows sometimes picks the wrong network profile after a restart or a network change, and you only notice by chance;
• a snapshot: checking now says nothing about what happened last night;
• remembering to check again, on every PC.

Coinetic works through the Windows Firewall that is already there. It does not see the other devices on your router; for that, the router's list stays the place to look. What it does is show and protect this PC's side: what reaches it, and what it sends out. No tool can promise 100% security, but you no longer have to guess.

• The profile stays where you put it: the Network Adapters page shows each network card and WiFi with its profile (Domain / Private / Public). Lock the profile, and Coinetic's protection service puts it back if Windows switches it.
• See your local network's traffic to this PC: the live log shows every allowed and blocked connection with the rule that decided it. Right-click it to filter to LAN (your local network) or internet traffic, so you see exactly which addresses on the WiFi tried to reach this PC.
• What is open, and to whom: the Open Ports page lists every program on this PC that waits for connections. The one-click security check compares them with the firewall rules and profiles and offers fixes you can undo.
• A port open to the internet? Coinetic closes it, or makes it invisible forever or until you unlock it from your phone.
• Nothing leaves without your OK: switch outbound control on for a network profile, and every new program asks once before it may connect out. Allow it, allow it only on your own network, or block it.
• At any time, not just once: this is not a one-time check. Open Coinetic whenever you like and see live what connects to this PC and from where. The Overview shows green when you are protected.
• Your AI security analyst (Pro + AI): right-click any line, program or connection and choose Ask AI, e.g. “Which devices on my network tried to connect to this PC today, and should I worry?”. It looks up this computer's Coinetic data itself and answers in plain words, with what to do on this machine.

Coinetic runs on Windows 7 to 11 and Windows Server 2008 R2 to 2025, in any Windows language.

More guides: all Coinetic guides.

Frequently asked

Can someone on my WiFi see what I do?

With WPA2 or WPA3, outsiders without the password can't read your traffic. Someone who is on your WiFi can see which websites your devices connect to, but with https:// not what you read or type. Setting your PC to Public keeps them away from your shared folders.

Can someone on my WiFi get into my PC?

Not by just being on the WiFi. They would need an open service on your PC (such as file sharing or remote desktop) and a weak password or an unpatched flaw. The Public profile, the Windows Firewall and updates close most of these doors.

Can Coinetic show me all devices on my WiFi?

No. Coinetic protects the Windows Server or PC it is installed on and shows what reaches that computer. The list of all devices on your WiFi is in your router.

I changed the WiFi password. Is that enough?

It locks out everyone who doesn't have the new password. Also change the router's admin password, switch off WPS and update the router, so nobody can simply read or reset the WiFi password from the router.