Https call not working in ios

Hello

My solution is set up with following version:

Ionic:

Ionic CLI : 6.13.1 (/usr/local/lib/node_modules/@ionic/cli)
Ionic Framework : @ionic/angular 5.1.1
@angular-devkit/build-angular : 0.803.29
@angular-devkit/schematics : 8.3.25
@angular/cli : 11.2.11
@ionic/angular-toolkit : 2.3.3

Cordova:

Cordova CLI : 10.0.0
Cordova Platforms : android 9.1.0, ios 5.1.1
Cordova Plugins : cordova-plugin-ionic-keyboard 2.2.0, cordova-plugin-ionic-webview 4.1.3, (and 12 other plugins)

Utility:

cordova-res (update available: 0.15.3) : 0.15.1
native-run (update available: 1.4.0) : 1.0.0

System:

ios-deploy : 1.11.4
ios-sim : 8.0.2
NodeJS : v15.13.0 (/usr/local/bin/node)
npm : 7.7.6
OS : macOS Big Sur
Xcode : Xcode 12.5.1 Build version 12E507

My problem is as follows:

Making https calls is working in android but not in ios. Making http calls is working in iOS but not in android.

I want to switch completely to https but can’t get it work in iOS.

Any hint because I’m quite stuck.

Thank you for your help.

Best Regards