stream_socket_client and server not working

I'm trying to create a connection between the client and the server (with TLS 1.2).

Client.php

$stream_context = stream_context_create(['ssl' => [
            'local_cert' => "path/to/cer.pem",
            'verify_peer' => true,
            'verify_peer_name' => false,
            'passphrase' => "password to cert",
            'verify_depth' => 0
        ]]);
$socket = stream_socket_client("tlsv1.2://127.0.0.1:8000", $errno, $errstr, 3, STREAM_CLIENT_CONNECT, $stream_context);

if ($socket === false) {
      return false;
 }

$req = "POST /Serwer.php HTTP/1.1\r\n" .
       "Content-Type: text/xml;charset=UTF-8\r\n" .
       "Host: 127.0.0.1\r\n" .
       "Connection: Close\r\n" .
       "Hello world!\r\n";

 $start = time();
 fwrite($socket, $req);
 $resp = '';

 while (!feof($socket)) {
    if (time() - $start > 15) {
        break;
    }

    $f = fgets($socket);
    $resp .= $f;
}

fclose($socket);
echo $resp;

Server.php

$stream_context = stream_context_create(['ssl' => [
    'local_cert' => "path/to/cert.pem",
    'passphrase' => "password to cert",
    'allow_self_signed' => true,
    'verify_peer' => false
]]);

$server = stream_socket_server("tlsv1.2://127.0.0.1:8001",$errno, $error, STREAM_SERVER_BIND|STREAM_SERVER_LISTEN, $stream_context);

if ($server === false) {
    return false;
}

$connects = array();
while (true) {
    $read = $connects;
    $read []= $server;
    $write = $except = null;

    $mod_fd = stream_select($read, $write, $except, 3); // return always 0, I don't know why
    if ($mod_fd === false) {
        break;
    }

    if (in_array($server, $read)) {
        $connect = stream_socket_accept($server, -1);
        $connects[] = $connect;
        unset($read[ array_search($server, $read) ]);
    }

    foreach($read as $connect) {
        $headers = '';
        while ($buffer = rtrim(fgets($connect))) {
            $headers .= $buffer;
        }
        fwrite($connect, "HTTP/1.1 200 OK\r\nContent-Type: text/html\r\nConnection: close\r\n\r\nHello!");
        fclose($connect);
        unset($connects[ array_search($connect, $connects) ]);
    }

fclose($server);

If I use in client and server one port, for example 8000, than i have error "address already in use". How do I check and accept the certificate and read the phrase ("Hello world") on the server side? Also I read that I need to use the command "openssl s_client -connect 127.0.0.1:8001", but I don't know how to use it in PHP and when exactly should I use. Thanks!

These two lines should be of particular interest to you

$socket = stream_socket_server("tcp://0.0.0.0:8000", $errno, $errstr);

$fp = stream_socket_client("tcp://127.0.0.1:8000", $errno, $errstr, 30);

Read this serwer&client