App deployed in ionic view can't connect to REST API (timeout error)

I deployed a build to Ionic Pro/View to share the app with testers however when i run it and tries to login it immediately gives http timeout error.
The REST API is at http://52.167.135.250:8081/mobileapi/v1.0/ URL so i’m wondering if a non standard port (not 80) could be a reason

Or may be this is because i use cordova-plugin-crosswalk-webview which is not listed in the supported plugins list?

Thanks