Uncaught exception from thread:Thread[com.jme3.network.kernel.tcp.SocketConnector@2569a1c5,5,main]
com.jme3.network.kernel.ConnectorException: Connector closed.
at com.jme3.network.base.ConnectorAdapter.run(ConnectorAdapter.java:162)
This error indicates that one of the connections dropped. I don't know why.
Some day the network layer will be modified to try to automatically reconnect them when they go down... especially if the others are still up.