At some point in the test on localhost, after prolonged number of requests sents and received to/from server, the Clients one by one, for unknown reasons, issue #PB_NetworkEvent_Disconnect event. After that, the Server continues to process without any reaction and not registering the #PB_NetworkEvent_Disconnect.
Most interesting that on the Server side it get yet #PB_NetworkEvent_Disconnect, but only after I close Clients applications.

Where is my omission?
PB 5.11