Laravel 5.6 Ajax login not working

I am trying authenticate user using ajax and redirect user to dashboard. Here is my code.

LOGIN FORM:

<div class="input-with-icon-left" title="Should be at least 8 characters long" data-tippy-placement="bottom">
    <i class="icon-material-outline-lock"></i>
    <input type="password" class="input-text with-border" name="password-register" id="password-register" placeholder="Password" required/>
</div>

<div class="input-with-icon-left">
    <i class="icon-material-outline-lock"></i>
    <input type="password" class="input-text with-border" name="password-repeat-register" id="password-repeat-register" placeholder="Repeat Password" required/>
</div>

AJAX:

        $('#login-form').submit(function (event){
            event.preventDefault();
          var results = '';  
          jQuery('#login_error').html('');
            $.ajax({
              type: 'POST',
              url: '{{ route ('user.login.post') }}',
              data: {email: $("#emailaddress").val(), password:$("#password").val()},
              dataType: "text",
              headers: {
                  'X-CSRF-TOKEN': $('meta[name="csrf-token"]').attr('content')
              },
              success: function (response) {
                var response = JSON.parse(response);
                if(response.success == false){
                    jQuery.each(response.errors, function(key, value){
                    jQuery('#login_error').show();
                    jQuery('#login_error').append('<p>'+value+'</p>');
                });
                } else {
                    window.location.href = response.redirectto;
                }
              }, error: function (xhr, status, error) {
                    jQuery('#login_error').show();
                jQuery('#login_error').append('<p>'+error+'</p>');
              }
          });
        });

MY WEB ROUTES:

Route::group(['as' => 'user.'], function() {

Route::post('login_manual', 'UserController@login_manual')->name('login.post');
Route::post('register', 'UserController@register')->name('register.post');
Route::get('logout', 'UserController@logout')->name('logout');

Route::get('dashboard', 'UserController@dashboard')->name('dashboard');

});

USER CONTROLLER:

public function login_manual(Request $request)  {  

  $validator = \Validator::make($request->all() , [
      'email' => 'required|email|max:255',
      'password' => 'required|min:6',
  ]);

  if($validator->fails()) { 
        return response()->json(['success' => false, 'errors' => $validator->errors()->all()]);
    } else {
        // create our user data for the authentication
        $userdata = array(
            'email'     => Input::get('email'),
            'password'  => Input::get('password')
        );
        // attempt to do the login
        if (Auth::attempt($userdata)) {
            return response()->json(['success' => true, 'redirectto' => 'dashboard']);
        } else {
            return response()->json(['success' => false, 'error' => ['Login Failed! Username and password is incorrect.']]);
        }
    }
}

If I trying to login with ajax it was giving me error "route[login]' not found. So I override the unauthenticated method of \App\Exceptions\Helper.php file to this:

/**
 * Convert an authentication exception into a response.
 *
 * @param  \Illuminate\Http\Request  $request
 * @param  \Illuminate\Auth\AuthenticationException  $exception
 * @return \Illuminate\Http\Response
 */
public function unauthenticated($request, AuthenticationException $exception)
{
    return $request->expectsJson()
                ? response()->json(['message' => $exception->getMessage()], 401)
                // : response()->json(['success' => false, 'error' => [$exception->getMessage()], 401]);
                : response()->json(['success' => true, 'redirectto' => 'dashboard']);
}

But now I am getting this JSON response on '/dashboard'

{"success":true,"redirectto":"dashboard"}

I didn't understand where I am doing wrong.