What is using my bandwidth? Find the device hogging your internet

Your router is the best place to find out. Most routers and ISP apps list every connected device, and many show how much data each one is using right now. If a single computer is the suspect, Windows Resource Monitor and macOS Activity Monitor show which app is sending or receiving the most. The usual culprits are cloud backups, game and system updates, and video streams in 4K.

Uploads deserve special attention. A photo backup or a big file sync can fill your upload completely, and that slows browsing, calls and games for everyone, even though no one is downloading much.

Step 1: Confirm something is actually hogging the line

Before you hunt, check that the connection really is busy:

1. Run the SpeedMetric speed test while things feel slow. Note download, upload and ping.
2. Pause what you can: close streaming apps, pause downloads, and turn off Wi-Fi on a few phones.
3. Run the test again.

If the second result is much faster, something on your network was using the bandwidth. If both results are slow, the problem is more likely the line, your provider or the Wi-Fi itself. Why is my internet slow? covers those causes.

A useful clue: if ping jumps when someone starts an upload or a download, the line is congested. SpeedMetric shows idle ping and jitter, not ping while the line is loaded, so watch for calls breaking up or games lagging the moment a backup starts. What is bufferbloat? explains why a full upload makes everything feel slow.

Step 2: Check the router for devices and traffic

Your router sees every device on the network, so it's the only place that can show the whole picture.

• ISP and mesh apps. Many providers and mesh systems have a phone app that lists connected devices. Some show live usage per device, and some let you pause a device with one tap.
• The router's web page. Type the router's address into a browser (it's usually printed on a label on the router) and sign in with the admin password from the same label or your own. Look for sections called "Connected devices", "Attached devices", "Traffic monitor" or "Bandwidth".
• Unknown devices. If you see a device you don't recognize, it may be someone using your Wi-Fi without permission. Change the Wi-Fi password.

Not every router reports per-device traffic. If yours only lists devices, use the elimination method instead: disconnect devices one at a time and run a speed test after each. When the speed jumps back, you've found the culprit.

Step 3: Find the app on a Windows PC

If one computer is responsible, Windows can show you which program is using the network.

• Task Manager. Press Ctrl + Shift + Esc, open the Processes tab and sort by the Network column. The top entries are using the most right now.
• Resource Monitor. In Task Manager, open the Performance tab and select "Open Resource Monitor". The Network tab lists every process with its send and receive rate in bytes per second.
• Data usage over time. In Windows 11, go to Settings > Network & internet > Advanced network settings > Data usage to see which apps used the most data recently. This is good for catching something that runs while you're away.

Step 4: Find the app on a Mac

Apple's Activity Monitor guide explains the Network view:

1. Open Activity Monitor (in Applications > Utilities).
2. Click Network.
3. Sort by Sent Bytes or Rcvd Bytes to see which processes have moved the most data.

The graph at the bottom shows data received and sent per second, so you can watch it spike when a particular app starts.

On phones and tablets, the mobile data screen in settings lists apps by data used. It's a decent way to spot a backup or streaming app that's busier than you thought.

The usual suspects

When people track down a bandwidth hog, it's usually one of these:

• Cloud backup and sync: iCloud, Google Photos, OneDrive, Dropbox and backup software uploading photos, videos or whole drives. These mostly use upload.
• Game downloads and updates: consoles and PC launchers downloading tens of gigabytes, often automatically at night.
• System updates: Windows, macOS, phones and smart TVs.
• 4K streaming: one 4K stream asks for 15–25 Mbps, so several at once add up quickly.
• Security cameras: each camera uploads video continuously or on every motion event.
• Torrent and peer-to-peer apps, which can use both directions heavily.

If your connection only struggles in the evening, it may not be a device at all. Why is my internet slow at night? explains how to tell household congestion from provider congestion.

Step 5: Limit it, rather than just switching it off

Once you've found the culprit, you have several options:

• Set limits in the app. Most backup tools, game launchers and update systems have a bandwidth limit or schedule setting. Steam, OneDrive and Windows Update all let you cap their speed.
• Schedule heavy jobs for overnight. Backups and updates finish just as well at 3 a.m.
• Use QoS on the router. Quality of service lets the router give priority to calls and games over bulk downloads. Not every router has it, and settings vary by model.
• Pause or block a device. Many router apps let you pause internet for a specific device, which is useful for a console downloading during work calls.

If uploads are the problem, limiting the backup's upload rate often fixes calls and gaming straight away. Why is my upload speed slow? covers other upload-side fixes.