Nick I think you are correct miniUPnP even if it is part of the UPnP Protocol Stack is more involved at the end of the Stack, if port forwarding is required by the device/appliance i.e. TV, receiver, etc...The second issue that I was having has more to do with the Simple Service Discovery Protocol even if SSDP was incorporated in the UPnP Protocol Stack not really related to miniUPnp tasks. In retrospect I confused the two different actions and I should probably have created a second forum entry for my second question.
But all is good with your help I was able to confine miniUPnP port forwarding to the interface of my choice, which is what I wanted. The second issue was to limit the access to my Standalone Server to port 8060 acting as an Emulated Roku device. I think I got that resolved by adding the following two custom rules.
I wish to apologize for the confusion with the interfaces. The interface: ens224 belongs to the Gateway Server HotLan, where the above interface: ens192 belongs to the Standalone server running the emulated Roku device. The first rule is to open the discovery process to the Harmony Hub, this is a standard SSDP process required for the discovery of devices. The second rule is for allowing the Harmony Hub access to the Emulated Roku Device.
For the audience that is wondering how can ClearOS become a Roku device? Well in this particular case it does for my Harmony Hub. The Harmony Remote activities sees the server as a Roku device and triggers Home Assistant events such as controlling lights, motorized curtains, etc... running on the same Standalone ClearOS server.
Thank you again to Nick for all the help.