Using VPN to login to IOT device

Hi. I have a device with a webserver that also has FTP and TCP capability. I am able to log in to the device and send commands when on the same local area network by enabling DHCP on the device and using the stated IP address.
I would like to use an RV50 to create a VPN, which I could join using my PC, to send comands to remotely and login via the webapp. I have near zero networking experience and trying to configure the RV50 in ACEmanager is proving to be beyond me. The RV50 manual is useless. I’ve tried setting up an IP Passthrough using an IPSec based VPN; however, as my poor mastery of the terminology is probably indicating, I have had no success. Suggestions would be helpful, a complete how-to would be even better.