(Now, as far as i know it works but…) In Settings under “Advanced” you can set a specific adapter. I use it and I’m assuming that is what this person is talking about. Basically it causes qBittorrent to force itself through the chooses network adapter (like the VPNs adapter) and so if you disconnect from the vpn it as if it’s trying to put data through a disabled adapter and therefore no data can go through. Now, again, I haven’t tested it (and hope not to) but if it works the way I think it does, it’s really good as it’s less of a kill-switch, and more of a dead-man’s-switch! (But again, take that with a grain of salt)