PHP router, separating frontend and backend?

Question

PHP

Good evening! Tell me the correct or more correct way to divide the WEB application into administrative and user parts. In this implementation, in fact, 1 more router will be connected, but already for the backend part. I think this is not good at all, then tell me where to dig.
In the code, I intentionally omitted error handling, and it's too early not to suggest frameworks.

<?php
/**
 *
 */
class Route
{
  public static function start()
  {
    $actionName = 'home';
    $controllerName = 'home';

    $routes = explode( "/", $_SERVER["REQUEST_URI"] );

    if( !empty( $routes[1] ) ) :
      $controllerName = $routes[1];
    endif;

    if( !empty( $routes[2] ) ) :
      $actionName = $routes[2];
    endif;

    $modelName = strtolower( $controllerName ) . "Model";
    $controllerName = strtolower( $controllerName ) . "Controller";
    $actionName = strtolower( $actionName ) . "Action";

    if( $controllerName == "adminController" ) :
      require_once 'app/backend/check.php';
      exit();
    else :

      $modelFile = "$modelName.php";
      $modelPath = "app/models/$modelFile";

      if( file_exists( $modelPath ) ) :
        require_once $modelPath;
      endif;

      $controllerFile = "$controllerName.php";
      $controllerPath = "app/controllers/$controllerFile";

      if( file_exists( $controllerPath ) ) :
        require_once $controllerPath;
      endif;

      $controller = new $controllerName;

      if( method_exists( $controller, $actionName ) ) :
        $controller->$actionName();
      endif;
    endif;
  }

}
 ?>

Answer 1

Two controllers: one for the frontend, one for the backend.