UltraVNC access to internal desktops

Last week our IP gateway was reset to correct an issue with using HTTPS to access it.  Since then the office administrator can't access her work machine from home using UltraVNC.  This did work prior to the gateway being reset by support.  Below are the steps that I have taken so far and I am sure I am just missing a step.

The IP address of the workstation is 10.1.10.12

UltraVNC server is set up on the workstation to communicate on port 5791 (not the real port being used )

Using IPChicken we found the routable internet address of the workstation 

I configured the IP Gateway to allow traffic to 10.1.10.12 on port 5791

We are not using static IP addresses but, it was working without it. 

My apologies - I forgot to mention that this is an SMC3DG appliance

Figured it out.  The port forwarding was not defined correctly. Once defined the issue was taken care of.