Firefox can't establish a connection to the server at wss://server_ip:port

Question

Am using Gos Web Socket Bundle and the application hosted on Apache server.

application config.yml

gos_web_socket:
server:
    port: 8000
    host: [SERVER IP]
pushers:
    wamp:
        port: 8000
        host: [SERVER IP]

Then Starting the websocketserver

php app/console gos:websocket:server 

and on client side 'twig'

 {{ ws_client() }}
    <script>
       var wsConnectUrl = "wss://{{gos_websocket_ip}}:{{gos_webscoket_port}}";
    </script>

when open the page with http the socket connected well. But when connect via https i got that errror

Firefox can't establish a connection to the server at wss://SERVER_IP:8000/

i found many solution on stackoverflow but nothing fix my issue this is the most referrals one Can not established Websocket secure connection on Firefox

Any help on that even with some clarification on above solution for my case here?

file /etc/stunnel/stunnel.conf

 # Certificate
 cert = /my/way/to/ssl.crt
 key = /my/way/to/not_crypted.key


 socket = l:TCP_NODELAY=1
 socket = r:TCP_NODELAY=1

 chroot = /var/run/stunnel4/
 pid = /stunnel.pid

 [websockets]
 accept = 8000
 connect = 8000