Why are chat reports showing high percent of 'Enduser was lost' (absent)?

Environment:  

Chat, End-user Pages

Issue:

Out of a fairly low volume of chats taken daily, many have a termination_event of 4 'End-user was Lost'.

Resolution:

This is generally seen when an end-user loses connectivity.  When the end-user is marked as absent, depends on the following configuration settings:

ABSENT_INTERVAL
USER_ABSENT_RETRY_COUNT

Please see Answer ID 4026: End-user absent in Chat message for more information on these settings.

Termination event of 4 does not necessarily mean the end-user had a problem.  Technically this termination event happens when the chat server does not receive any communication from the end-user for more than 4 minutes.  One way this can happen is if there are network issues or if an error happens.  However there are other reasons this can happen and any action that interrupts communication will result in this termination event if the agent lets the chat end automatically.

Many mobile devices function in a way that can lead to increased occurrences of this termination events.  If the end-user closes the browser app without disconnecting from chat the OS will stop communication and the chat will result in this termination event after 4 minutes. This commonly seen in end-user behavior originating from devices using iOS (Apple's mobile operating system, common on devices such as iPhones). When an end-user navigate's from chat to a different application on the phone the communication to the chat server is stopped by iOS and resumes when the end-user returns to the chat as long as the end-user did not get disconnected form the chat while they were away.

For example if you are engaged in a chat with an agent and the end-user uploads a file in chat or navigates to a different app on the phone. The end-user will see the following messages when they resume the chat.
Communication with the Oracle B2C Service Chat service has been lost. Please wait while attempts are made to restore the connection. 
Disconnection in XXX seconds. 
Connection resumed.
This is expected when using an iOS device such as an iPhone. Oracle does not control this behavior. 

Another common situation that leads to this termination event is users with laptops that are configured to go into Sleep mode when the cover is closed.  There is no way to confirm this without talking to the end-user but one indication is to look at the chat discussion (i.e. did both the agent and the end-user indicate they have completed their discussion).