External Portal server?

Hello everyone, this is my first time posting here.

I’ve been having a little trouble trying to configure Captive Portals on a Balance 30 Pro using InControl2.
We provide connectivity to consumers and businesses and because we collect analytics (user counts, etc.), and use several hardware vendors, we use our own external Portal server.

However when attempting to configure this on any of our Peplink products we have not found any option to use our Server instead of Peplink’s built-in portal.
Is there any possible way to bypass the built-in portal and instead use our own Portal server?