Following tutorial, I've setup realtime script and unity game.

But in unity, OnPacketReceived(packet) were not executed.  Where rest of configured function were execute correctly.

Seems like it not getting corresponding sending function on realtime script. By logger, I can confirm that the setInterval() was settled.

What the problem here? Do I misunderstand anything? Or the send() function just not worked?

man, is your data sent by UDP? there are problems every now and then, depends on how do you set it up . search for UDP ticket, you will realise that you are not the only one...