Hello,
In the old version, if the client request a protocol and the server doesn't support this protocol, the connection was not closed. This was fixed some time ago, if the client sends a protocol and the server doesn't accept this protocol in the header "Sec-WebSocket-Protocol" the connection is closed.
If you check the log, you will see that the client sends the following header in the request:
Sec-WebSocket-Protocol: WAMP
While the server, although accept the connection, it doesn't sends this protocol in the response, so this means the server doesn't support the protocol.
Kind Regards,
Sergio