One thing to try would be to use TCP for your transport (RTSP uses UDP by default for its actual RTP stream payloads):
pullstream uri=rtsp://theaddress:554/streamname localstreamname=mystream forcetcp=1
Other than that, you will need to start opening up some restrictions in your firewall. RTSP works like this:
1 connection via RTSP over TCP (by default port 554)
This establishes the connection and handles the handshake, which then establishes up to 4 more connections:
RTP: port unknown (negotiated). UDP or TCP, video traffic
RTCP: port unknown (negotiated). UDP or TCP, video traffic synchronization
RTP: port unknown (negotiated). UDP or TCP, audio traffic
RTCP: port unknown (negotiated). UDP or TCP, audio traffic synchronization
If you see the handshake, but are not seeing the actual traffic, your firewall is preventing the other connections from … connecting.
Bryan