Hi, There is an issue at Firefox version 40, where we are getting this error: "Firefox can't establish a connection to the server at wss://...". From the server side (Apache Server), the handshake is properly done, upgrading to WebSockets. Firefox does not show that gets any response and this error is returned. This happens only behind a corporate firewall, everything is ok in an open network Wifi or mobile network. Also remark that there is no issue at corporate Proxy side, since this is working properly at Google Chrome browser. Do you have any idea how to solve this maybe in JavaScript? Is this a typical issue? Find attached a screenshot from the web console, with the network and headers details from the WSS request. BR, Jesus