I'm using the official WireGuard client, which does not have such a tickbox unfortunately. I only know of one other client app for Windows : Tunsafe. Unfortunately, Tunsafe does not seem to work anymore. This was the main reason I started using the official WireGuard app. When I started using WireGuard, there was no official client yet, and Tunsafe was about the only way to make it work with Windows. Tunsafe was smart enough to exclude my LAN by itself though...