Laravel 5.4 set and increment custom session variable

Im new to Laravel. Im trying to set a counter of failed login attempts by using sessions. However I not able to make it work. Here is my UserController handling registration, login and logout. I wanna have a global variable, which I can access from the login form and force user to use CAPTCHA if there is more than 2 failed logins

public function postSignIn(Request $request)
{
   $failedAttempt = Session::get('FailedAttempts');
   if(!isset($failedAttempt)) $failedAttempt = 0;

    $this->validate($request, [
        'email' => 'required',
        'password' => 'required'
    ]);
    if (Auth::attempt(['email' => $request['email'], 'password' => 
           $request['password'], 'active' => 1])) {
        return redirect()->route('dashboard');
    } else {
        $failedAttempt++;
        Session::put('FailedAttempts', $failedAttempt);
        dd("Counter: " . $failedAttempt); //<- Always 1!!!
    }

$failedAttempt never gets incremented on the next failed login attempts. I've tried Session::set('FailedAttempts', $failedAttempt);, session(['FailedAttempts' => $failedAttempt]); but still no luck

via Chebli Mohamed