Web RTC in a Symmetric NAT situation does not work on FF, Aurora and Nightly because TURN is not supported/buggy. I have tried setting media.peerconnection.turn.disable flag at "about:config" for both peers to true, however it does not solve it. To reproduce it, go to apprtc.appspot.com using the 3 browsers and try to join using another peer on a different network using one of the browsers mentioned. The Web RTC reference application only works as intended if and only if the peers are on the same network. On Wireshark logs, I do not see TURN requests to any TURN server. The Web application works perfectly on Chrome.