Define the failure you are protecting against
A VPN connection can stop because a network changes, a device sleeps, the server becomes unavailable, or the app is closed. A kill switch attempts to prevent selected traffic from falling back to the ordinary network path during some of those states.
The phrase sounds simple, but implementations differ. Some products block all non-VPN traffic; others depend on operating-system “always-on” or “block connections without VPN” features. Some allow local-network access. Read the provider and platform documentation before assuming a specific behavior.
Android has system-level VPN controls
Android supports always-on VPN and can be configured to block connections that do not use the VPN. Those are operating-system capabilities; an individual VPN app still needs to work correctly with them. Menu names can differ by Android version and device manufacturer.
If you enable a blocking mode, test ordinary tasks afterward. Local printers, casting devices, captive portals, or apps intentionally excluded from the VPN may behave differently. Make one change at a time so you know which setting caused a problem.
Test transitions, not just a steady connection
A useful test includes the moments when routing changes. Connect the VPN, verify normal browsing, switch between Wi-Fi and mobile data, and observe whether the VPN reconnects. If your platform exposes a block-without-VPN option, check what happens while the tunnel is intentionally disconnected.
Do not use a single IP-check page as proof that every application is covered. Split tunneling, local-network exceptions, and application-specific networking can create different results.
Treat it as one layer
A kill switch can reduce accidental fallback traffic, but it does not protect an account from phishing, stop a malicious app from reading data it already has permission to access, or make an unsafe download trustworthy. Keep the control in its proper role: managing network routing during VPN interruptions.
Sources & further reading
This guide is general educational material. Platform behavior can change by version, device, network, and provider configuration.
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