EXTJS Ajax Request without response

Question

I´m trying to do a Ajax Request to a Server from my mobile App. When testing on my Pc with localhost I´m able to connect and get the data. But when testing this from my mobile phone I cant even get a connection. I could swear it worked some builds ago and then suddenly stopped working.

When fireing the ajax reqeust the server doesnt show any log entries.

Tried to set the default xhr header in my ajax to false.

my ajax

Ext.Ajax.request({
        url: myUrl,
        method: 'POST',
        username: 'someuser',
        password: 'somepw',
        withCredentials: true,

        //useDefaultXhrheader:false,


        params: {
            //localStorage.getItem('UUID'),
            appDeviceID: '4d55a4-4e97a3-aaf5e1-887afea5f0de-334aef', //example uuid
            controller: 'appLogin',
            username: username,
            passwort: password
        },
        success: function (response, eopts) {
            var result = Ext.decode(response.responseText);

             console.dir(result);



            if (result.success === true) {
                console.log("Login erfolgreich");

                //Login erfolgreich -> UserDaten Speichern
                localStorage.setItem("LoggedIN", true);
                localStorage.setItem('USER_DATA',result.userData);

                //LoginView zerstören
                meThis.getView().destroy();

                //weiter zur Main
                meThis.redirectToMain();

            } else {
                console.log("Login nicht erfolgreich");

                localStorage.setItem("LoggedIN", false);

                meThis.setTextToHiddenLaben('Eingabe Falsch!');

                //Eingaben aus dem Login Form löschen
                var form = Ext.getCmp('login');
                form.reset();
            }

        },
        failure: function (response, eopts) {
            localStorage.setItem("LoggedIN", false);
            console.log('Serverside failure with statuscode: ' + response.status);
            console.log(response);

        }

    });

-working with modern toolkit only

Anyone a idea what the problem is?

Greetings