When dealing with these issues, it is a very good idea to always use port explicitly, even if it is default for a protocol. This prevents Flash from doing an internal protocol rollover which is slow and not in your control.
Flash HTTP (Sanjose) streaming is another option. This uses HTTP to deliver video and audio chunks similarly to Smooth and Cupertino streaming. So this does not have any RTMP related issues. However there are few security options with Sanjose streaming. The tutorials cover configuration and playback of Sanjose streams.