Only one answer can be returned to client by a server when using UDP with netty?

I suspect your decoder has some problem so that it store the received data into its internal buffer without finishing decoding. To confirm this, I would add a LoggingHandler to the beginning of the pipeline to log what really has been received (or not). If the LoggingHandler logs that something was received but TesterChannelHandler is not getting the message, it's likely that the decoder is buggy.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.