Playing around with open ports and firewall rules.
RealNetworks has a good testing site: http://service.real.com/test
RealNetworks content servers and clients use the following communications:
Usually it is initiated by HTTP (such as access to a *.RAM file which really is a single line text file pointing to the real file or stream.)
Then it uses HTTP, RTSP (Real Time Streaming Protocol), or PNA protocols for streaming
TCP 554 (RTSP) -> <- UDP 6970-32000
or TCP 7070 -> real audio <- UDP 6970-7170