Wow thank you, this is the most useful reply I’ve received so far!

This means I don’t need to mess around with QBT’s “proxy” settings? I was pretty confused since the only options available are SOCKS/SOCKS5 and HTTP, but I’m guessing that’s a different kind of proxy than what I need…

Resetting the “time since last being told I don’t know shit on the internet” back to 0 once again…

I already have an existing and working setup used for other apps, it’s close to the one described in this blogpost. Yes, it’s complicated and inefficient, but it has reasons to be. I want to keep my qBittorrent configuration as close to this setup as reasonably possible for consistency. If your point is that it’s counterproductive to follow this setup then… fair enough. I can just route traffic from the VPS to an exposed port on the local qBittorrent container over Wireguard, but that wasn’t my preferred solution.

Running a torrent client through a proxy doesn’t isolated a process.

I was talking about network isolation, not process isolation.

make sure your traffic is routing there properly

That was pretty much what I was asking for help with.

I have already set up all of that. My setup is similar to the one in this blogpost and it’s already working for various apps that only use HTTP. What I’m trying to do is to also route BitTorrent traffic (TCP/UDP) over the same setup without opening up entirely new paths.

Yes I already have that set up with Wireguard, what I’m figuring out is how to route traffic through it.

I’m guessing what you mean is setting up port forwarding in Wireguard…

The thing is ideally I would want all connections in and out of my homeserver’s Docker network to go through the local Caddy proxy, so the app containers are isolated. That still means having at least the local Caddy acting as a TCP proxy, even if the VPS Caddy is bypassed. If that’s too much of a hassle though I can instead just expose a port on the qBittorrent container directly to the homeserver’s localhost, and forward that with wireguard to the VPS.

By “set up wireguard to route through the VPS” you mean having wireguard forward a port from the VPS to a port on the homeserver at its wireguard IP address?

qBittorrent will still need to publish the right IP address to peers though, right? So I will need to configure the proxy VPS’s IP address in qBittorrent…

Also that means binding a port on the qBittorrent container directly to the homeserver localhost. I’ve managed to keep the app containers isolated so far and it’d be nice to keep that, but if proxying the traffic is too annoying I guess I can just say fuck it and go with it.