Quick idea of blocking external access with PHP

MY_Controller.php

<?php
class MY_Controller
{
  private function ipVersion($ip)
  {
      return strpos($ip, ':') === false ? 4 : 6;
  }
  
  public function isLocal()
  {
      $userIP = $_SERVER['REMOTE_ADDR'];
      $serverIP = $_SERVER['SERVER_ADDR'];
      if ($this->ipVersion($userIP) == 4) {
          if ($userIP != '127.0.0.1' && $userIP != 'localhost'){
              $userIP = explode('.', $userIP);
              $serverIP = explode('.', $serverIP);
              if ($userIP[0] == $serverIP[0] && $userIP[1] == $serverIP[1]){
                  return true;
              } else {
                  return false;
              }
          } else {
              return true;
          }
      } else {
          $checkUserIPv6 = strpos($userIP, 'fe80:') === false;
          if ($userIP != '::1' && $userIP != 'localhost' && $checkUserIPv6){
              if ($userIP[0] == $serverIP[0] && $userIP[1] == $serverIP[1]){
                  return true;
              } else {
                  return false;
              }
          } else {
              return true;
          }
      }
  }
}