[markusjm@localhost compress]$ php --version
PHP 5.6.22 (cli) (built: May 26 2016 14:22:49)
Copyright (c) 1997-2016 The PHP Group
Zend Engine v2.6.0, Copyright (c) 1998-2016 Zend Technologies
[markusjm@localhost compress]$ cat compress.php
<?php

// $client_flags = 0;
// works fine

 $client_flags = MYSQLI_CLIENT_COMPRESS;
// hangs

$mysqli = mysqli_init();

$mysqli->options(MYSQLI_OPT_CONNECT_TIMEOUT, 10);

$hostname = '127.0.0.1';
$username = 'maxuser';
$password = 'maxpwd';
$port = 4008;
$database = '';
$socket = '';

$mysqli->real_connect($hostname, $username, $password, $database, $port, $socket, $client_flags);

if ($mysqli->connect_errno) {
    echo "Failed to connect to MySQL: (" . $mysqli->connect_errno . ") " . $mysqli->connect_error;
}

echo $mysqli->host_info . "\n";

$res = $mysqli->query("SELECT @@server_id id, @@hostname host");


while ($row = $res->fetch_assoc()) {
    echo " res = " . $row['id'] . ' : ' . $row['host'] . "\n";
}

?>