Laravel 5.5 administrator route issue

I have the below mentioned route:

Route::get('/', 'HomeController@index');
Route::get('administrator', array('before' => 'auth', 'uses' => 'Administrator\IndexController@index'));
//Route::get('/administrator', 'Administrator\IndexController@index');
Route::group(['prefix' => 'administrator'], function() {

Route::get('login', 'Administrator\IndexController@index')->name('login');
 Route::post('login', 'Auth\LoginController@doLogin'); 
 Route::get('logout', 'Auth\LoginController@logout');
});

My intention is when someone try to access http://127.0.0.1:8000/administrator/ this will go directly to the login page of the administrator.

However, when I tried to access the same, it said 404 not found.

via Chebli Mohamed