Magento – Magento 2: Submitted Form not calling Controller

To continue with the question below

Magento 2: How to define Scope For Router.php

app\code\Custom\Module\view\frontend\templates\posts\view.phtml

<form class="form post reply"
      action="<?php /* @escapeNotVerified */ echo $block->getSaveUrl(); ?>"
      id="post_reply_form"
      name="postReplyForm"
      method="post"
      data-hasrequired="<?php /* @escapeNotVerified */ echo __('* Required Fields') ?>"
      data-mage-init='{"validation":{}}' 
    >
    <fieldset class="fieldset required">
        <?php echo $block->getBlockHtml('formkey') ?>
        <div class="field post_reply_description required">
            <label class="label" for="post_reply_description"><span><?php /* @escapeNotVerified */ echo __('Message') ?></span></label>
            <div class="control">
                <textarea name="post_reply_description" id="post_reply_description" title="<?php /* @escapeNotVerified */ echo __('Description') ?>" class="input-text" cols="5" rows="3" data-validate="{required:true}"></textarea>
            </div>
        </div>
    </fieldset>
    <div class="actions-toolbar">
        <div class="primary">
            <button type="submit" title="<?php /* @escapeNotVerified */ echo __('Submit') ?>" class="action submit primary">
                <span><?php /* @escapeNotVerified */ echo __('Submit') ?></span>
            </button>
        </div>
    </div>
</form>

app\code\Custom\Module\Block\Posts\ViewPosts.php

namespace Custom\Module\Block\Posts;

use Magento\Framework\Registry;
use Magento\Framework\View\Element\Template;
use Magento\Framework\View\Element\Template\Context;
use Magento\Framework\App\Filesystem\DirectoryList;
use Magento\Framework\Data\Collection;
use Magento\Framework\Filesystem;
use Magento\Framework\Image\AdapterFactory;
use Magento\Framework\Message\ManagerInterface;
use Magento\Store\Model\ScopeInterface;
use Magento\Framework\App\Config\ScopeConfigInterface;

class ViewPosts extends Template {

    /**
     * @var Registry
     */
    protected $coreRegistry;

    /**
     * @var ModuleURL
     */
    protected $ModuleURL;

    /**
     * @var _filesystem
     */
    protected $_filesystem;

    /**
     * @var _imageFactory
     */
    protected $_imageFactory;


    /**
     * @param Context $context
     * @param Registry $registry
     * @param array $data
     */
    public function __construct(
    Context $context, Registry $registry, Filesystem $filesystem, AdapterFactory $imageFactory, ScopeConfigInterface $scopeConfig, array $data = []
    ) {
        $this->coreRegistry = $registry;
        $this->_filesystem = $filesystem;
        $this->_imageFactory = $imageFactory;
        $this->scopeConfig = $scopeConfig;


        parent::__construct($context, $data);
    }

    protected function _prepareLayout() {
        parent::_prepareLayout();
        return $this;
    }

    /**
     * Return the Url for saving.
     *
     * @return string
     */
    public function getSaveUrl() {
        return $this->_urlBuilder->getUrl('mymodule/posts/postReplyForm');
    }
}

app\code\Custom\Module\Controller\Posts\PostReplyForm.php

namespace Custom\Module\Controller\Posts;

use Magento\Framework\App\Request\DataPersistorInterface;
use Magento\Framework\App\ObjectManager;
use Magento\Framework\App\Filesystem\DirectoryList;

class PostReplyForm  {

    /**
     * @var DataPersistorInterface
     */
    private $dataPersistor;

    /**
     * Post user post
     *
     * @return void
     * @throws \Exception
     */
    public function execute() {
        $post = $this->getRequest()->getPostValue();

        echo "<pre>";
        print_r($_REQUEST);
        exit;
   }
}

What's reason why it's not going in controller file?

[UPDATE]

https://github.com/tzyganu/Magento2SampleModule/blob/master/Controller/Router.php

It's going to line number 151 & returing 404 page.

I would like to define scope (as my previous question) that when there is only detail page with .html extension then only it will call Router.php file otherwise it works as it is.

Trying to do patch over here

app\code\Custom\Module\Controller\Router.php

Which causes another error for redirection

if ($postsURLSuffix) {
    $suffix = substr($urlKey, -strlen($postsURLSuffix) - 1);
    if ($suffix != '.' . $postsURLSuffix) {
        // START FOR POST MESSAGE FORM REDIRECT
        if (strpos($request->getServer('REQUEST_URI'), 'postReplyForm') !== false) {
             $redirectURL = "http://localhost".$_SERVER['REQUEST_URI'];
             $resultRedirect = $this->resultFactory->create(ResultFactory::TYPE_REDIRECT);
             $resultRedirect->setPath($redirectURL);
             return $resultRedirect;
        }
        // END FOR POST MESSAGE FORM REDIRECT
        return false;
    }
    $urlKey = substr($urlKey, 0, -strlen($postsURLSuffix) - 1);
}

Which gives fatal error

Fatal error: Call to undefined method
Magento\Framework\Controller\Result\Redirect\Interceptor::execute() in
D:\wamp\www\magento2\vendor\magento\framework\App\FrontController.php
on line 57