Kill Switch in a VPN: what it is, why you need it, and how to turn it on

A kill switch is a safety catch: if the VPN tunnel drops, the device does not go straight to the open internet but waits until the connection comes back. Without it, for seconds or minutes after a drop, websites and apps see your real address, and your provider sees your traffic. In the NvoVPN app on a computer it is a single toggle; on Android it is a system one. Below is how to turn on the kill switch in four steps, what exists on iPhone, and how to check that it works.

1. 1

   Disconnect and open Kill Switch

   On a computer: while the VPN is connected, the setting is locked — the app will say so: disconnect first. Press the shield to disconnect, then open "Settings" → "Application" → "Kill Switch".

2. 2

   Choose a mode: Soft or Strict

   "Soft KillSwitch" blocks the internet only if the VPN drops unexpectedly; switch the VPN off yourself and the internet works as usual. Right for most people. "Strict KillSwitch" blocks the internet whenever the VPN is not connected: after a manual disconnect and before the app has even started. The same screen has "DNS exceptions" — DNS server addresses that stay reachable while the internet is blocked; rarely needed, for a corporate network, say.

3. 3

   On Android, turn on the system toggle

   On Android, the "Kill Switch" item in NvoVPN's settings leads to the system settings: "Settings" → "Network & internet" → "VPN" → the gear icon next to NvoVPN. Turn on "Always-on VPN" — the system will keep the tunnel up and bring it back after a restart — and "Block connections without VPN": that is the kill switch, available since Android 8. The toggles only appear after you have connected through NvoVPN at least once.

4. 4

   Check that it works

   Strict: connect, then disconnect the VPN with the button — sites will not open until you reconnect. Soft: simulate a drop — connect over Wi-Fi, then turn off Wi-Fi on the router or switch to mobile data; the internet disappears until the app reconnects. Once it recovers, open "What is my IP" — it shows the server's address.

What a kill switch does

While the VPN is connected, all traffic goes through the encrypted tunnel. The tunnel can drop: Wi-Fi disappears, the phone switches to mobile data, the server restarts, a carrier throttles the protocol. Normally the system immediately lets traffic through directly — and apps keep working, just unprotected now. A kill switch forbids that: until the tunnel is back up, there is no internet at all. To messengers and the browser this looks like a brief "no network", but your real IP never leaks out.

There are two levels. At the app level, the VPN app itself blocks traffic; at the system level, the operating system does — and that works even if the app is closed. NvoVPN has the first level on computers, and on Android the app hands off to the system one — it is more reliable: the block holds even if the app is unloaded.

iPhone and iPad: what exists, and what does not

iOS has no kill switch for ordinary users: an always-on VPN only exists on corporate devices managed through MDM. The "Connect On Demand" setting in a VPN profile is not a substitute: it only tries to reconnect, and if that fails, traffic goes out directly. What helps in practice: keep the NvoVPN app connected, turn on "Maximum reliability" on the home screen so the connection uses a block-resistant channel and drops less often, and do not turn off the VPN on public networks.

Windows and macOS

Neither Windows nor macOS has a system kill switch, so use the one built into the app (steps 1–2): on computers it works at the app level and blocks the traffic of every program. Advanced users can additionally configure the Windows firewall: block all outgoing traffic and allow it only through the VPN adapter and for the app itself. For most people, that is overkill.

When to turn it on, and when not to

• Turn it on if you use public Wi-Fi, work with sensitive data, or it matters to you that not a single request slips past the tunnel.
• You can leave it off if you only need the VPN for a handful of sites, and short connection gaps bother you more than an address leak: in stealth mode, and when switching networks, reconnecting takes a few seconds.

FAQ

Does a kill switch slow the internet down? No — it is a blocking rule, not traffic processing. Only the tunnel itself affects speed.

How is it different from auto-connect? Auto-connect brings the VPN up when the app starts; a kill switch forbids traffic until the VPN is up. They work together: one restores the connection, the other closes the window of exposure.

Does it work if the app is closed? On Android, the system's "Block connections without VPN" does. In the desktop app, Strict mode applies even before it launches; Soft only while the app is running.

Why did the internet disappear after an update? That is how Strict mode behaves when the VPN has not connected yet. Open the app and connect — or switch the mode to Soft.

Related guides: Why VPNs stop working and how stealth mode works · How to install a VPN on Android · What to do if the VPN will not connect