The torrenting issue is easily solved by binding your VPN interface in qBitTorrent.
The other issue “wireguard app vs. proprietary VPN app” is a little more tricky, but I’ve been there myself, so here’s my 2¢:
I logged into my VPN account and downloaded a conf file for my chosen location for each individual device. Then imported it into the wireguard app, and activated it. Then kept an eye on ipleak and the wireguard app (I use two screens).
First handshake was very fast, and the connection stable, and a re-handshake at 2 mins. faultless… but after a while within the same session, streaming stuttered, and would sometimes just stop. Files would upload, then delayed uploads etc. Handshakes would take longer and longer. Here I would deactivate the tunnel, then immediately re-activate it. Then that slowly deteriorating process would start all over again again.
Next day, on waking the device (I use on a daily basis MacBook, iPhone, Android phone, Win 10), there’d be no connection available. Re-activation didn’t change anything. Here I would need to deactivate the tunnel, go to my VPN account and re-download a conf file (which was sometimes for the exact same server, sometimes for a different server). Then it’d be like a brand new wireguard connection, and the same as I wrote above.
Biggest problem with the wireguard app in conjunction with a VPN provider, is that the app can’t monitor the imported connections, and flip to one that’s available - you need to do that manually. If it could do that, then you wouldn’t need the proprietary VPN app from your provider.
It seems to me that the inherent instability of wireguard when purchased from a VPN provider, is caused by a server overload… or put very simply, most VPN providers don’t own or rent sufficient server space to deal with the demand.
Source:
I thought the same about the wireguard app and the minimal resources needed to run it, and tried various experiments over the course of several weeks. In the end, I reverted back to the proprietary app.