All that's required is to set up the appropriate routing rule for the desired traffic to go through the VPN. Leave the default route as is. I do this when I use OpenVPN to connect to my home network. I even had it set up so that when I connected to the Rogers SMTP server, it would appear as though I was connecting from home. (This was before I learned about using port 587 for off network SMTP.)but only have the Huludesktop app use the VPN connection all other traffic should go out not over the VPN.