Laravel auth重定向

I have trouble redirecting after user authentication. I would like to redirect admin to admin panel, and user to home so I made admin middleware:

public function handle($request, Closure $next)
{
    if (Auth::user() && Auth::user()->isAdmin()) {
        return $next($request);
    }

    return redirect('/');
}

Routes for admin panel are:

Route::prefix('admin')->middleware(['web', 'admin', 'auth'])->group(function () {

    Route::get('/', 'HomeController@index');
    Route::resource('user', 'Admin\UserController');

});

I have User and Role models in a M-2-M relationship.

User model:

public function role(){
    return $this->belongsToMany('App\Role');
}

public function isAdmin()
{
    return ($this->role->first()->name == 'Admin') ?  true : false;
}

Auth LoginController:

protected $redirectTo = '/admin';

Auth RedirectIfAuthenticated:

public function handle($request, Closure $next, $guard = null)
{
    if (Auth::guard($guard)->check()) {
        return redirect('/');
    }

    return $next($request);
}

Issue I'm having is that I always end up on home page. When watching through the inspector I noticed something strange, don't know if it is a standard procedure or not:

Login seems to be triggered twice? Route to /admin was triggered and got 200 OK status, but I never got to see it. If I manually enter it to the browser however, it will lead me to the admin dashboard.