Hi Jason
And to elaborate on one of the other workarounds that I touched on in the support case (which I've had time to expand here with an example).
For requests forwarded to specific port, you can add a "Service Resolution" so that all requests on that Listen Port : 8082 here, directs the traffic to testProxy service - note that it does not matter what the URI value is, it is always forwarded onto the testProxy service.
Then in the testProxy service we can do a pattern match for those URI's that are acceptable on port :8082.
If none are acceptable we return a template 401 response.
Otherwise we forward the request to another port, here localhost:8080 which resolves those services as normal.
So the above method gives us another way to allow only a small sample of services to be accessible via a specific port.
Cheers - Mark
PS: I agree the Idea/enhancement request to allow selection of which interface is usable would be a useful addition to the gateway. The solution Mark He explained, with two API Gateways is probably the more normal way I have seen this done.