Ionic 3 Cordova ajax calls fail on Windows 10 (UWP) - ajax

Question

I have attempted to ask this previously, buy got no real answers, and have now been struggling for over a month.
I just cannot get my ajax calls to work on an Ionic 3 Cordova application built for a Windows 10 UWP. They can access localhost, but not any outside connections.
The application works fine on both Android and iOS.
I am trying to test this locally on my dev machine. I use a certificate (bought) to sign the application, install this certificate, build the application for Windows, and am able to open up the built CordovaApp.Windows10_1.0.1.1_x86.appxupload, and then double click the embedded CordovaApp.Windows10_1.0.1.1_x86.appx file to install, which completes successfully. The install indicates the app need internet access.
In the config.xml, I have the following tags, as suggested elsewhere...
<allow-navigation href="*" />
<access origin="*" />
However, when I run, the http.get call just returns 0 with no other information. I can run in Visual Studio, and look at the returned error object, and get no further info, apart from this 0 return.
I have run fiddler, enabled the https decryption as explained here, but all I see in the response header is
HTTP/1.0 200 Connection Established
FiddlerGateway: Direct
StartTime: 13:44:21.686
Connection: close
The result in the main view actually shows 200, so I don't think this is showing me anything real.
I am at a complete loss. I have no where else to search. What could I be missing?
Should I be able to use external ajax on a Windows 10 machine, when I have sideloaded the application as here? I haven't tried from the store yet, as I don't want to upload until I know it works.
Any suggestions desperately welcomed. Surely someone has had an Ionic 3 application accessing external ajax working?
Thanks in advance for any help
[UPDATE 1]
If I run the application on the same machine, just using Ionic serve (so it just runs in the browser rather than hosted in the UWP), the ajax calls also work fine.
[UPDATE 2]
I have now created a Cordova application using the Visual Studio template, so taking all other frameworks out of the equation.
I used vanilla JavaScript to do my rest call...
document.addEventListener('deviceready', callUrl, false);
function callUrl() {
console.log('callUrl');
var xhr = new XMLHttpRequest();
xhr.open('GET', 'https://myserveraddress.com/myapp/testroute');
xhr.send(null);
xhr.onreadystatechange = function () {
var DONE = 4; // readyState 4 means the request is done.
var OK = 200; // status 200 is a successful return.
if (xhr.readyState === DONE) {
if (xhr.status === OK)
console.log(xhr.responseText);
} else {
console.log('Error: ' + xhr.status);
}
}
};
I run this in the debugger, and even here I get an error (status code of 0).
Another thing I noticed when I open up the build package and look at the cordova_plugins.js file..
My Ionic app has the following...
cordova.define('cordova/plugin_list', function(require, exports, module) {
module.exports = [
{
"id": "cordova-plugin-console.logger",
"file": "plugins/cordova-plugin-console/www/logger.js",
"pluginId": "cordova-plugin-console",
"clobbers": [
"cordova.logger"
]
},
{
"id": "cordova-plugin-console.console",
"file": "plugins/cordova-plugin-console/www/console-via-logger.js",
"pluginId": "cordova-plugin-console",
"clobbers": [
"console"
]
},
{
"id": "cordova-plugin-device.device",
"file": "plugins/cordova-plugin-device/www/device.js",
"pluginId": "cordova-plugin-device",
"clobbers": [
"device"
]
},
{
"id": "cordova-plugin-device.DeviceProxy",
"file": "plugins/cordova-plugin-device/src/windows/DeviceProxy.js",
"pluginId": "cordova-plugin-device",
"merges": [
""
]
},
{
"id": "cordova-plugin-splashscreen.SplashScreen",
"file": "plugins/cordova-plugin-splashscreen/www/splashscreen.js",
"pluginId": "cordova-plugin-splashscreen",
"clobbers": [
"navigator.splashscreen"
]
},
{
"id": "cordova-plugin-splashscreen.SplashScreenProxy",
"file": "plugins/cordova-plugin-splashscreen/www/windows/SplashScreenProxy.js",
"pluginId": "cordova-plugin-splashscreen",
"runs": true
},
{
"id": "cordova-plugin-statusbar.statusbar",
"file": "plugins/cordova-plugin-statusbar/www/statusbar.js",
"pluginId": "cordova-plugin-statusbar",
"clobbers": [
"window.StatusBar"
]
},
{
"id": "cordova-plugin-statusbar.StatusBarProxy",
"file": "plugins/cordova-plugin-statusbar/src/windows/StatusBarProxy.js",
"pluginId": "cordova-plugin-statusbar",
"runs": true
},
{
"id": "ionic-plugin-keyboard.KeyboardProxy",
"file": "plugins/ionic-plugin-keyboard/src/windows/KeyboardProxy.js",
"pluginId": "ionic-plugin-keyboard",
"clobbers": [
"cordova.plugins.Keyboard"
],
"runs": true
}
];
module.exports.metadata =
// TOP OF METADATA
{
"cordova-plugin-console": "1.0.5",
"cordova-plugin-device": "1.1.4",
"cordova-plugin-splashscreen": "4.0.3",
"cordova-plugin-statusbar": "2.2.2",
"cordova-plugin-whitelist": "1.3.1",
"ionic-plugin-keyboard": "2.2.1"
};
// BOTTOM OF METADATA
});
Now, I notice every plugin in the module.exports.metadata also has an entry in the module.exports EXCEPT for cordova-plugin-whitelist!
If I open the same file for the Corvoda application created in VS, I see the following...
cordova.define('cordova/plugin_list', function(require, exports, module) {
module.exports = [];
module.exports.metadata =
// TOP OF METADATA
{
"cordova-plugin-whitelist": "1.2.2"
};
// BOTTOM OF METADATA
});
So this has nothing else for the whitelist plugin as well
Could there be something missing here?? Could this white-list plugin not be installed correctly?

Answer 1

I had a similar situation where my ajax calls worked fine in TEST, but when I moved to PROD, they would fail.
The answer was finally tracked down as a missing intermediary certificate on the server I was trying to access. TEST had the cert, PROD did not.
I hope this helps.