I tested that RTSP URL, and for me it does not disconnect. I suspect that it’s either something with your network connection, but more likely your machine. Does the problem occur on other networks? Does the problem occur with another machine on the same network? Is there a problem with the VLC version you have installed?
If you have the same error on your own Wowza installation, then check the Wowza logs, maybe it tells more about the reason for disconnecting.
Or maybe VLC is just generally tired of playing Big Buck Bunny - it must have done that a zillion times worldwide now …