Laravel 5 "The page isn't redirecting properly" What is the reason for this route?

I got "The page isn't redirecting properly" problem when I use Route::controller('/', 'DashboardController'); In routs.php file. If I using Route::get('/', 'DashboardController@getIndex'); I don't have this problem.In my AuthController.php I use protected $redirectTo = '/'; for redirect. My Question is why I got this error?

routs.php

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Route::group(['middleware' => 'auth'], function () {
Route::group(['prefix' => 'products'], function () {
        Route::controller('category', 'Products\ProductsCategoryController');
        Route::controller('manufacturer', 'Products\ProductsManufacturerController');
        Route::controller('/', 'Products\ProductsController');
    });

    Route::group(['prefix' => 'customer'], function () {
        Route::controller('category', 'Customer\CustomerCategoryController');
        Route::controller('/', 'Customer\CustomerController');
    });

    Route::group(['prefix' => 'reports'], function () {
        Route::controller('/', 'Reports\ReportsController');
    });

    Route::controller('/', 'DashboardController');
});

Route::auth();

Route::get('/home', 'HomeController@index');

via Chebli Mohamed