In some environments, it is critical that when a user stops using a session, the session is closed to the host. Since it is unreliable to capture a browser being closed (or actually killed with Task Manager), the lostSessionTimeout can be used as a "dead man switch".
When lostSessionTimeout is set to something other than 0 (zero), that will set the number of minutes that the FVTerm server logic will wait in-between any activity from the client before automatically closing the session.
When websockets are active, a ping is sent every 20 seconds, unless an enter or keystroke has been sent in the meantime. Since there can be delays in the websocket (or plain HTTP environment), the minimum recommended setting for lostSessionTimeout is 2 minutes. 5 minutes probably provides the best balance between network error recovery and user's browsers being closed without ending the session.
Example:
<add key="lostSessionTimeout" value="5"/>
