Recently I had the problem that some Java based applications (e.g. Apache Directory Studio and JXplorer) were not able to connect to other servers on my Windows 7 machine. After some investigation I realized that the reason for that was the fact that Java tries to connect via IPv6 if IPv6 is supported by the OS. Unfortunately, even if no connect is possible Java seems to not retry via IPv4 in this case.
So you either need to disable IPv6 on your machine or you need to add the parameter “java.net.preferIPv4Stack=true” to the settings.
For Apache Directory Studio you add that parameter to the file <program dir>\configuration\config.ini. For JXplorer you add the parameter “-Djava.net.preferIPv4Stack=true” (make sure you include the “-D”!) to the command line in the “jxplorer.bat” file.