Is it possible to use a server (using PHP) to send an IOS Push Notification?

Question

I am trying to send push notifications using a web server and PHP. I have tried to use the code from an answer to a similar question (https://stackoverflow.com/a/45676540/11051450), but I cannot make it work for some reason. I have figured that this might be because this code was not ment for a web server. In the linked answer they also emphesize that you need curl version 7.38.0, but I think my web server only have curl version 7.29.0. This is the code that I have tried to use:

<?php

  $keyfile = 'AuthKey_AABBCC1234.p8';               # <- Your AuthKey file
  $keyid = 'AABBCC1234';                            # <- Your Key ID
  $teamid = 'AB12CD34EF';                           # <- Your Team ID (see Developer Portal)
  $bundleid = 'com.company.YourApp';                # <- Your Bundle ID
  $url = 'https://api.development.push.apple.com';  # <- development url, or use http://api.push.apple.com for production environment
  $token = 'e2c48ed32ef9b018........';              # <- Device Token

  $message = '{"aps":{"alert":"Hi there!","sound":"default"}}';

  $key = openssl_pkey_get_private($keyfile);

  $header = ['alg'=>'ES256','kid'=>$keyid];
  $claims = ['iss'=>$teamid,'iat'=>time()];

  $header_encoded = base64($header);
  $claims_encoded = base64($claims);

  $signature = ''; //should I put a password here?
  openssl_sign($header_encoded . '.' . $claims_encoded, $signature, $key, 'sha256');
  $jwt = $header_encoded . '.' . $claims_encoded . '.' . base64_encode($signature);

  // only needed for PHP prior to 5.5.24
  if (!defined('CURL_HTTP_VERSION_2_0')) {
      define('CURL_HTTP_VERSION_2_0', 3);
  }

  $http2ch = curl_init();
  curl_setopt_array($http2ch, array(
    CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_2_0,
    CURLOPT_URL => "$url/3/device/$token",
    CURLOPT_PORT => 443,
    CURLOPT_HTTPHEADER => array(
      "apns-topic: {$bundleid}",
      "authorization: bearer $jwt"
    ),
    CURLOPT_POST => TRUE,
    CURLOPT_POSTFIELDS => $message,
    CURLOPT_RETURNTRANSFER => TRUE,
    CURLOPT_TIMEOUT => 30,
    CURLOPT_HEADER => 1
  ));

  $result = curl_exec($http2ch);
  if ($result === FALSE) {
    throw new Exception("Curl failed: ".curl_error($http2ch));
  }

  $status = curl_getinfo($http2ch, CURLINFO_HTTP_CODE);
  echo $status;

  function base64($data) {
    return rtrim(strtr(base64_encode(json_encode($data)), '+/', '-_'), '=');
  }

?>

So my question is as the title explains if you are able to send a push notification to a IOS device using a web sever and if can give me a hint to how I should do it/is doing wrong?