It would be nice to know the exact error message that minecraft gives you. "outdated server" means your minecraft version is too new. "Identication serves are down" usually means you have to uninstall and reinstall minecraft to connect to servers again. and if you get a long computercodey looking thing maybe like this "java.nullpointer.emeraldfoxconnectionrefused no further info." then that means that the server is currently rebooting and you can get on in like 5 minutes.