Hi,
What FOP2 version are you using? Try disabling websockets in /var/www/html/fop2/js/presence.js (and flush your browser cache after the change).
FOP 2.27 supports secure websockets (wss), the reason is it still in beta is because websockets is still undergoing implementation changes on browsers. One of the "gotchas" on using ssl/tls is that brwosers require you to accept the certificate as you do it when browsing an https site with a self signed certificate, but when you use websockets, there is no confirmation window to accept the certificate, thus the wss connection stalls.
I have also seen some websocket connections failings when passing through certain routers (connetion worked fine within the same LAN, but failed when connecting via the internet through a router). The flash xmlsocket worked on this cases, but for some reason websocket connections failed.
