I am not familiar with Torguard VPN. On their website they mention a “OpenVPN config generator”. Have you tried to generate an ovpn-config file that can be uploaded to the MT300N-V2 via the device´s webgui?
BTW: I found that the option “Force VPN (No Internet if VPN is not connected)” has some problems in my individual config, e.g. no data transfer to some local subnets. Without this option everything works fine.