Module Create Failed

I’m using Virtualmin control panel on my server. I am using WHMCS as a billing software. In WHMCS I have set up the server info correctly (hostname is, IP, nameservers, correct username and password) and I have checked the “Tick to use SSL Mode for Connections” checkbox. I have selected the option to “Automatically setup the product as soon as the first payment is received”. I am getting this error when a client makes an order and pays the invoice:

Error: Curl Error: 35 - error:140770FC:SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol

Basically it fails to create an account in the virtualmin.

What does the error mean? And how do I fix it?

did you add :10000 after the IP?
did you pass that error to Matt?

Yes I added the port :10000 after the IP. I am going to pass the error to Matt, thanks.