Best method for selective network interface usage? (Proxy?)

Ive been trying to make qbittorrent-nox allow me to force usage strictly on Tun0 (the VPN). This is how i use the GUI version and it makes a killswitch unneeded. When my VPN is down, it simply cannot work.

Ive tried forcing the config into the nox but it is just not available. I then decided to just let the vpn manage everything on the system as soon as dietpi boots, but this breaks system time and forces me to manage firewall rules for each specific thing.


all the other torrent management apps supplied also seem to not allow you to just select an network interface. its driving me nuts because its just the easiest way to assure you dont attempt to download over your home ISP. So simple, i can let me family use it without worry.

What would be the best method to protect yourself using dietpi and its optimized app list? Could I have OpenVPN Client connect to my VPN but only used via proxy? Like, can i have OpenVPN start on system boot, connect but nothing go through it unless i manually specify? something, anything that would almost give me the same exact functionality as what i want form qbittorrent?

below is an example of what i am referring to. also, i use surfshark so i have never tried the nordvpn/dietpi app