Messaging server and all the clients fail when a client's IP address is fouled up in a specific way.
There was a bad glitch in the DD system on Tuesday June 2, 2015 at 17:16:33. The server lost track of all of its clients, and the clients all lost track of the server. Neither the server or any of the clients properly recovered until I rebooted them all.
At that time on Tuesday, I believe I turned on the Dynamic Displat software on the new NUC in Erik’s office driving a 4K TV. (It is way cool—everyone should go have a look!) However, the NUC’s internal reckoning of its IP address was incorrect. It looked like it connected properly to the messaging server, so I rejoiced and went home.
That IP Address mistake was fixed on Thursday morning.
I see nothing in the Java code that would have caused that, unless it is within the implementation of the Java class java.net.Socket, java.io.ObjectOutputStream or java.io.ObjectInputStream.
There is a note in gov.fnal.ppd.dd.chat.MessagingServer at about line 158, which is where the connection code exists.