Direct answer
When you diagnose or configure a VPN kill switch, “setup” mainly means defining what should happen to network traffic when the VPN connection drops, and “decisions” means choosing the operating conditions (for example, which interfaces or apps are affected) and the safety behavior you expect. In practice, the kill switch watches for connectivity changes and then blocks (or reroutes) traffic according to your configuration.
How it works
A VPN kill switch is typically designed to limit data leaks by reacting to states such as: the VPN tunnel not being established, the connection failing, or the VPN going down after it was previously working. Your configuration choices determine the scope of protection—common choices include restricting traffic only for the VPN tunnel, applying rules to all network traffic on the device, or targeting specific network paths and apps. During diagnosis, you’re trying to confirm that the block triggers at the right moment and that it doesn’t break everything you still need for troubleshooting.
Decision points you’ll encounter include: what counts as “connected” (fully established tunnel vs. partially negotiated state), what happens on reconnect attempts, and which network types (Wi‑Fi vs. mobile) the rule applies to.
Practical context for a user configuring or diagnosing
Use a controlled test approach rather than relying on assumptions. First, confirm baseline behavior with the VPN connected and verify normal traffic can reach intended destinations. Then simulate failure conditions that mirror real issues you’re investigating—such as toggling the VPN off, changing networks, or causing brief connectivity loss—and observe whether non‑VPN traffic is blocked as intended. If the kill switch blocks too much, you may need to adjust scope so you can still access the device’s network settings or support tools.
It helps to validate using multiple signals (for example, whether your visible IP changes as expected when the VPN is up, and whether traffic is limited when the VPN drops). Because exact behavior varies by device and VPN client, plan tests around your specific environment rather than expecting identical results everywhere.