VPN Kill Switch Explained: What It Does and How to Test It

VPN connections drop more often than you might think: when a laptop wakes from sleep, when a phone switches from Wi-Fi to mobile data, or when a server restarts. For a few seconds, your device falls back to your normal, unprotected connection. A kill switch stops that from happening.

What a kill switch does

A kill switch blocks all internet traffic whenever the VPN is not connected. If the tunnel drops, your apps lose their connection instead of quietly continuing without protection. As soon as the VPN reconnects, traffic flows again.

Without one, a download, a messaging app or a browser tab can keep sending data over your real connection during those gaps, revealing your IP address.

The two kinds of kill switch

System-level (also called "always on" or "network lock")

Blocks traffic from the whole device unless the VPN is connected. This is the stronger option and the one most people should use.

App-level

Closes or blocks only the apps you choose, for example a torrent client or a browser, when the VPN drops. Useful if you want some apps, such as your bank's app, to keep working without the VPN.

Where to find it

Windows and macOS: in the VPN app's settings, usually under "Connection", "Security" or "Kill switch".
Android: Android has a built-in option. Go to Settings → Network & internet → VPN, tap the gear next to your VPN, and turn on Always-on VPN and Block connections without VPN.
iPhone and iPad: many VPN apps offer a setting that keeps the tunnel enforced. Turn on "Connect on demand" or the equivalent option in the app so the VPN reconnects automatically.

How to test your kill switch safely

Turn the kill switch on and connect the VPN.
Start something that uses the internet continuously, such as a video or an IP check page that refreshes.
Simulate a drop. The cleanest way is to disconnect Wi-Fi for a few seconds and reconnect, or switch the VPN to another server, which briefly closes the tunnel.
Watch the page or video: it should stop loading while the VPN reconnects, then resume.
Check an IP test site once it reconnects. It should show the VPN's address.

If pages keep loading during the drop while showing your real IP address, the kill switch is not working. Update the app, make sure the system-level option is selected, and try again.

Common questions

Will a kill switch cut my internet when I disconnect the VPN myself?

That depends on the app. Some keep blocking until you turn the kill switch off; others only act on unexpected drops. If you lose internet after manually disconnecting, check the kill switch mode.

Does it slow down my connection?

No. A kill switch only acts when the VPN is down. It has no effect on speed while connected.

Do I need it at home?

If privacy at home matters to you, yes, because leaks happen at home too. On public Wi-Fi it matters even more; see our public Wi-Fi checklist.

Choosing a VPN with a reliable kill switch

Look for a system-level kill switch on every platform you use, plus DNS leak protection. Nova VPN Premium includes both. Not sure how to turn it on? Ask us in the chat and we will guide you.