Many people are having problems because their multiclient in their gpk patch is outdated here is the easy thing to do
REQUIRED
(GPK BYPASS EVEN OUTDATED)
Download Sandboxie(Just Google It)
Steps
1) Open sandboxie
2) Launch your dragonest launcher.exe dont press the start yet!
3) drag your dragon nest launcher.exe to your sand boxie and select default then press OK!
VOILA!
You can use multiclients