I had this problem before. Are you making sure that you are not closing cygwin to kill the MUD's connection? Also if your IP adress constantly changes that could also be the problem. Make sure your using the IP adress that comes up on your command prompt.
If you don't know
Open Command prompt Type in Ipconfig Then look where it says IP Adress that should be the adress you should be giving out to your friends.
Secondly, that advice is incorrect. In this case the issue is not that his friends don't know his IP address, but that their connections are being refused. Furthermore, even if he hadn't given the correct IP to his friends, ipconfig would not necessarily help him. In my case, for example, it tells me my internal IP address - that information is somewhat useless if I want people outside of my own network to connect to my PC. As Zeno and Cratylus said 5 months ago, the problem is a router/firewall issue and is likely something to do with port forwarding.
Thirdly, I've come to expect better from you, David Ha- … oh wait.