Symfony2 Session object is always empty, no session, no authentication
I am using symphony 5 with php Ratchet like in the examples. Unfortunately it is not possible to my to get the user session. I need to get the authenticated user's data, the userid, or at least some session value that I defined before. But the session is always empty. The setup is running in a docker container in a virtual machine (ubuntu). The symfony and the websocket server are running on the same ip (e.g. 192.168.190.100, not localhost or 127.0.0.1).
I am able to retrieve some cookie values with $conn->httpRequest->getUri()->getHost(); but the session values are still empty.

Run the Websocket Server:
```
$server = IoServer::factory(
    new HttpServer(
        new SessionProvider(
            new WsServer(
                new WebSocketCommunicator()
            ),
            new MySessionHandler())

    ),
    $this->_websocketPort
);

$server->run();

```

Function onOpen in WebSocketCommunicator:
```
public function onOpen(ConnectionInterface $conn, RequestInterface $request = null)
{
	echo "URI: " . $conn->httpRequest->getUri()->getHost();
	echo "KEY: " . $conn->Session->get('key');
	
	// URI contains something
	// KEY is empty but was set before

	// Attach new client
	$this->clients->attach($conn);
}

```

Does anyone have a working example or an idea what I'm doing wrong? Thank you so much!