How can I create a UDP server in Python that is possible to know when a client has disconnected? The server needs to be fast because I will use in an MMORPG. Never did a UDP server then I have a little trouble.
UDP is not connection-based.  Since no connection exists when using UDP, there is nothing to disconnect.  Since there is nothing to disconnect, you can't ever know when something disconnects.  It never will because it was never connected in the first place.
UDP Server in Python