I would be concerned about where it was installed and where it's reading it's registry entries from.
Remember, you can't share configuration files in C:/Program Files/Priston Tale between the launcher and the game, or the game and... IDK... Notepad, for example. They are private, locked, and unique to each individual "sandboxed" program. (all programs installed in normal locations
are "sandboxed" in Windows Vista, 7 and 8)
Likewise, no two programs can share the registry settings in HKEY_LOCAL_MACHINE on those newer OS. (again, because they run in their own little sandbox, and are not allowed to "play" with other programs, or the rest of the system... that's naughty XD)
Still, if you have followed the guides and "tried all the stuff here" to resolve this, you already know that it is reading the correct configuration files, and have traced the IP and Port it's actually trying to open a connection to and send packets on. Right DucNguyen?
Knowing that basically proves that the connection is firewalled... but if you haven't done that confirmation yet, please go back and re-check.