fetch data from web API working in the browser but not working in the device ionic app

i build ionic app project . and fetch data from SQL server using web API . the project working in the browser but not working in the device

here the code

synAccountFromServer() {
    this.dataServices.getAccountFromServer().subscribe(
      d => {
        alert('Data Success');
      },
      err => {
        console.log('Error11: ' + JSON.stringify(err));
      }
    );


getAccountFromServer() {
    //alert('start get Datat from serve');   
    return this.http.get(this.urlGetAccounts);
  }