Torrent Traffic through VPN
I have tried to set up NAT to take any traffic from 192.168.1.5 (main machine running qBittorrent) on port 1555 (torrent port) through OPT1 gateway (VPN Interface) with no luck. A firewall rule from 192.168.1.5 with source 1555 gets me the ability to download, but connecting to peers and DHT, not so much. I don't want to enable UPNP, but I cannot figure out how to NAT correctly. All of the guides I have found don't have traffic routed through any interface other than WAN.
Did you check with your VPN provider that they support port forwarding through the VPN tunnel?
Are you sure you can ID the traffic with a source port?