PHP Server SSL WebSocket receives binary garbage - php

Question

I'm having deep trouble with implementing a PHP server websocket. It works completely fine without SSL.
However, when I switch client to "wss://" and add SSL context to the server socket, I get random binary garbage after client connects. I searched everything on the web but cannot figure it out.
Client code does basically nothing:
var ws = new WebSocket('ws://127.0.0.1:8888');
ws.onopen = function() {
console.log('ws open');
}
Here is the minimal PHP code for SSL-less connection which works fine:
<?php
$socket = stream_socket_server(
'tcp://127.0.0.1:8888',
$errno, $errstr,
STREAM_SERVER_BIND | STREAM_SERVER_LISTEN
);
$cn = stream_socket_accept($socket, 99999, $name);
$text = fread($cn, 1024);
echo $text;
?>
With it, and client using "ws://", I receive normal WebSocket upgrade request which I can process. Everything is fine.
Now, I change client call to "wss://" and add SSL to server:
$context = stream_context_create();
stream_context_set_option($context, 'ssl', 'local_cert', '../ssl/cert.pem');
stream_context_set_option($context, 'ssl', 'allow_self_signed', true);
stream_context_set_option($context, 'ssl', 'verify_peer', false);
$socket = stream_socket_server(
'tcp://127.0.0.1:8888',
$errno, $errstr,
STREAM_SERVER_BIND | STREAM_SERVER_LISTEN,
$context
);
and this time I receive some binary encoded data which I'm unable to process:
▬♥☺☻☺☺♥♥{8T▬↕↑/Б{Ҭh#_W l0w2♣9x(j‹~Y{A∟MTT
::‼☺‼☻‼♥+/,0̨̩‼¶/5☺☺↨☺☺
↕►♦♦♦☺♣♣♣♠♠☺↕3+)**☺↔ JtD~[}▼$▲ɒNt◄vCyw-☻☺☺+♂
**♥♦♥♥♥☻♥☺♥☻☻ ☺§
I also tried all kinds of keys and certificates for SSL. I used Apache and Nginx certs, I created them manually with OpenSSL, I created them with PHP code that I found on web, nothing helps. I reproduced this on Windows and Ubuntu systems with PHP7.4 and Apache and Nginx web servers, used localhost and external IP addresses, does not differ.