

This is why the most foolproof solution I’ve found is to use a docker container that has VPN and torrent client built-in. It’ll have the networking configuration done by someone who knows better. The most popular ones, like this, would permit no internet access out of the container outside of the VPN host. Then it doesn’t matter whether the torrent client binds to a specific interface or not, or what its configuration is. It’s trapped, or sandboxed, and the only way out is via the VPN tunnel. Once you have setup one of these, you can also reuse it from other containers with other apps, like your Usenet client, or even outside of containers via the built-in HTTP proxy. I know there’s also a qBit based container but I haven’t read into it or used it so I can’t vouch for it. The Transmission-OpenVPN based one is rock solid. Have used it for many, many years.
I outlined some differences that could make it worth it over just interface binding for some. Another is that it makes it impossible to accidentally have another application exit through the tunnel, leaking your identity, like a browser logged into gmail.com. You have to explicitly set the container as proxy in the browser for that to become possible. It also allows using a separate VPN connection, provider or region for the torrent client, while the desktop user is free to use a different VPN connection or none.