We have a multiplayer game with client/server architecture, using only NetworkTransport (no HLAPI). Basically, there is a special MonoBehaviour that performs Receive and Send in FixedUpdate both on client and server.
Sometimes when player disconnects, server application crashes with the next native stack trace:
UNET crash: NetworkTransport crashes the game on connect/disconnect
Sometimes when player disconnects, server application crashes with the next native stack trace: