Does the client player give any indication of what the problem might be? For example, it might show "buffering...", which would indicate that the data rate is too slow.
Does the display on Broadwave show that you are reconnecting? Does it show whether you are still streaming audio, or just silence?
The starting point would be to work out whether Broadwave is streaming continuously, but only 20s of audio and the rest of silence; or on the other hand, the stream is ok, but the data rate is too low for the connection.
Another possibility is that the pc is too busy to encode in real time. Use Task Manager to check the cpu usage.