Use gluetun, look up how to configure for your provider. Run a 2nd container for your torrent client, using network_mode: “service:gluetun” to run all your traffic though the vpn. Note that if you’re forwarding ports from your client to e.g. access the web UI, you’ll need to forward them from the gluetun container instead.

If you want to use transmission as your torrent client I recommend checking out https://github.com/haugene/docker-transmission-openvpn . There are some additional configuration changes needed for mullvad but it should be straightforward.

My (almost finished) script creates a setup like this. It doesn't just do a client + VPN, but it can also set up radarr, sonarr, jellyfin, and a couple of other services

https://gitlab.com/hyperspace_/lootarr

Just google "gluetun + qbittorrent". There are some examples, but in short you want network_mode: "service:gluetun" and depends_on: -gluetun under qbittorrent so it doesnt have connection if gluetun fails.

Gluetun supports a lot of providers, documentation is decent and simple.

But consider airvpn or any other with port forwarding if you want to torrent. Mullvad ditched PF recently 😔

Don‘t use two images, just use qbittorrentvpn

I use portainer for stacks so idk how you do it manually... But a stack with Gluetun and any apps that you use the VPN. I have Firefox(kasm) in my stack with the homepage set to ipleak to double check the VPN

https://hub.docker.com/r/qmcgaw/gluetun

I figured you wanted a 4th person telling you to use Gluetun. The biggest advantage is that it can run anything through the VPN. Not just the torrent client, but also radarr, sonarr, slskd, etc

I recently went through setting this up. I can give you a base compose.yaml based on the one I have

For the wireguard config, you would throw your .conf file to /path/to/wireguard/config, like so: /path/to/wireguard/config/wg0.conf

This setup assumes you have ipv6 working and enabled. The wg0.conf would also have the VPNs ipv6 address. I use Mullvad too btw.

You can access Qbittorrent's web UI through http://localhost:8090.

I'd like to note that the image I use for Qbittorrent has support built in for VPN, but with the setup I have I basically have the wireguard container with its network, and multiple containers on that same network. In theory it should work with other bittorrent clients.

And the docker images for reference:

• https://hub.docker.com/r/linuxserver/wireguard
• https://hub.docker.com/r/dyonr/qbittorrentvpn

version: '3.7'
services:
    wireguard:
        image: lscr.io/linuxserver/wireguard:latest
        container_name: wireguard
        cap_add:
          - NET_ADMIN
          - SYS_MODULE #optional
        networks:
          - wireguard_network
        environment:
          - PUID=1000
          - PGID=1000
          - TZ=Etc/UTC
        volumes:
          - /path/to/wireguard/config:/config
          - /lib/modules:/lib/modules #optional
        ports:
          - 51820:51820/udp   # Wireguard
          - 8090:8090         # QBittorrent
        sysctls:
          - net.ipv4.conf.all.src_valid_mark=1
          - net.ipv6.conf.all.disable_ipv6=0
        restart: unless-stopped

    qbittorrentvpn:
        privileged: true
        container_name: qbtwg
        network_mode: service:wireguard
        depends_on:
            - wireguard
        volumes:
            - '/path/to/qbtconfig/:/config'
            - '/path/to/downloads/:/downloads'
        environment:
            - VPN_ENABLED=no
            - VPN_TYPE=wireguard
            - PUID=1000
            - PGID=1000
            - LAN_NETWORK=192.168.1.0/24
            - 'NAME_SERVERS=1.1.1.1,1.0.0.1'
        restart: unless-stopped
        image: dyonr/qbittorrentvpn
networks:
  wireguard_network:
    driver: bridge

I don't do it all in one compose file out of preference, but as others have said Gluetun + your preferred torrent client with all networking going to Gluetun. I've been running this way with deluge for a while now and it's been solid as a rock.