Basically, the problem is pretty big. We are running the latest version of Tekkit. When she puts up the server, only 1 friend and herself can get on it, and a majority of us can't. The server doesn't even register us attempting to log in. Our clients basically says it doesn't exist. We tried to do it with default Minecraft, but it didn't work. This was after my friend tried to run a Team Fortress 2 server, and it did work. We have no idea if there's a connection between it. She tried closing the ports for the TF2 server, and we tried it again with both Tekkit and default, and nothing is working at all. The ports are properly forward, and the server has been running fine in the past both on Tekkit and on default.
Server not working--Help?