Accessing SpeedFusion VPN via Peplink DDNS

I have an older android/AppleIOS app that is used to control a marine AC unit that requires a DDNS address to remotely access an onboard thermostat on a boat. I’m attempting to access it via a Peplink MAX BR1 Pro 5G via cellular.

My solution was to setup a FusionHub VM with a SpeedFusion VPN to the MAX BR1 Pro 5G on the boat then setup the DDNS link to the FusionHub VM.

I have setup and have communicating both a Peplink DDNS link, and a SpeedFusion VPN via a FusionHub VM. However, the Peplink DDNS service takes me to the Remote Web interface via TCP 5246.

Is the DDNS hard coded to point at the Web Interface, or is there a way to route the DDNS traffic to the SpeedFusion VPN?

Basic Diagram of what I am proposing.