You may have port forwarded 28200 correctly but your server is definitely not 28200. Make sure your server's port is 28200.
For the issue with certain servers not connecting make sure they also port forwarded, UPnP sometimes works on certain clients, not always. If they did port forward, no idea what the issue is. Could be an issue with the matchmaker, I've tried connecting to the matchmaker and it did time out. getMatchMakerIP() for anyone who wants to get the IP of the matchmaker.