The live will attempt to connect an RTMP connection through port 1935 by default. If port 1935 fails, port 443 is attempted next. If this port fails, the stream will attempt to establish RTMPT (RTMP Tunneled) on port 80, because most firewalls allow communication on HTTP port 80.
If RTMPT on port 80 fails, it is likely that you have a "stateful inspection" firewall that rejects any non-HTTP packets on port 80.