The bug

When the client gets disconnected from a server (for example because it was kicked, timed out or an exception occurred) the message is not logged and additionally for exceptions the stacktrace is not logged either.
NetworkManager.exceptionCaught(ChannelHandlerContext, Throwable) logs exceptions only with the logging level DEBUG, which makes sense for the server, but not for the client.

Expected behavior:

• "Regular" disconnects (kicked, timeout?): Message is logged as "Info"
• "Unexpected" disconnects: Message is logged as "Error" including exception stacktrace

Note that the logged message for a packet error (at DEBUG level) also has a typo ("Failed to sent packet") and is used even for receiving an invalid packet, not just sending.