Thank you Ravi,
Opening port 554 (and 1755) did the trick!
| Hi Noel,
| Are you using WMS9 and are the users who are not able to receive the
| the ones with the WMP9 player?
| If so, this could be because you haven't opened port 554 (the default port
| for RTSP) on the firewall. The WMP9 client will connect to a WMS9 using
| RTSP (and then HTTP), so you will need to open port 554 on the firewall.
| This posting is provided "AS IS" with no warranties, and confers no