Laravel 5.3: Create Admin Middleware

I created a Middleware called Admin

public function handle($request, Closure $next)
{
    if (Auth::guard($guard)->check())
    {
    if(Auth::user()->isAdmin())
        return redirect('/list_host');
    else {
   // return $next($request);
      return redirect('/home');
    }
    }


}

IsAdmin looks like this:

 public function isAdmin()
    {
        return $this->is_admin;
    }

And their I want to check if the user is logged in and has admin-rights. I also added it to Kernel.php

 protected $routeMiddleware = [
        'auth' => \Illuminate\Auth\Middleware\Authenticate::class,
        'auth.basic' => \Illuminate\Auth\Middleware\AuthenticateWithBasicAuth::class,
        'bindings' => \Illuminate\Routing\Middleware\SubstituteBindings::class,
        'can' => \Illuminate\Auth\Middleware\Authorize::class,
        'guest' => \App\Http\Middleware\RedirectIfAuthenticated::class,
        'throttle' => \Illuminate\Routing\Middleware\ThrottleRequests::class,
    'admin' => \App\Http\Auth\Middleware\Admin::class,
    ];

And then I use it in the Routes/web.php

Route::get('/list_hosts', function()
{
    return view('/list_hosts');
})->middleware('admin');

Unfortunately also none Admins can view the Site. Any suggestions?

via AppleForTheKing