Connection failed: No such file or directory (IONOS)

Question

I keep receiving Connection failed: No such file or directory when opening my php files hosted on IONOS , even tho the files path are correct and the connection is working

this is the connection example script

<?php
  $host_name = 'test.hosting-data.io';
  $database = 'dbstest';
  $user_name = 'dbutest';
  $password = 'test';

  $link = new mysqli($host_name, $user_name, $password, $database);

  if ($link->connect_error) {
    die('<p>La connexion au serveur MySQL a échoué: '. $link->connect_error .'</p>');
  } else {
    echo '<p>Connexion au serveur MySQL établie avec succès.</p>';
  }
?>

none of the solutions of similar questions worked for me