Ionic 4 - Works on Android, not on IOS

I´ve got a app that does a simple REST call to a external endpoint. Works well when running ionic serve.

Deploying this on my Android Device it works and it download the data from the endpoint.
Deploying on my Iphone, it does not work and give me the following error:

2019-02-12 23:03:41.229522+0800 rpg-flw-4[606:145510] {"headers":{"normalizedNames":{},"lazyUpdate":null,"headers":{}},"status":0,"statusText":"Unknown Error","url":"<someurl>","ok":false,"name":"HttpErrorResponse","message":"Http failure response for <someurl>: 0 Unknown Error","error":{"isTrusted":true}}

Does this make sense to anyone? Give me some hints to why this would happen?

Have you adjusted the config.xml file to allow access to that endpoint?

The config.xml has <access origin="*" />

Bit of discussion of this error here…

I put this comment here to help people who will face with this error in the future.
If every solutions don’t work, you could try this Ionic 4 android 9 CLEARTEXT http not permitted error