The problem
Server time calculation in Metin2 client uses only one packet to synchronize it. Server sends current timestamp once, client adjusts time according to it. If packet retreival is late so is calculated offset. This results in desynchronized in game interface, ex. affects are visible in the affect shower 2 seconds longer than they are actually applied.
The fix
Solution is fairly simple: by periodically measuring the Round Trip Time (RTT) and factoring in half of that delay to calculate the exact network offset, the client can continuously synchronize its clock with the server.
