PowerBI Embedded: net::ERR_CONNECTION_REFUSED

Currently testing sample web app.

Made very few modifications to rest of code, added simple "filter" form field (does nothing) in the default.aspx. No changes with embed URL objects.

Early tests were successful! No issues. Client/Secret keys are added properly. Very pleased with the PowerBi service and functionality.

Enterprise gateway is setup. Testing imported report as well as DirectQuery report. Neither load, endless animation.

Browser console has message: net::ERR_CONNECTION_REFUSED

I sense this must be a very simple problem, any advice?

Sample JS:

var m = { action: "loadReport", accessToken: accessToken };
            message = JSON.stringify(m);

            // push the message.
            iframe = document.getElementById('iFrameEmbedReport');
            iframe.contentWindow.postMessage(message, "*");