Session timeout is an important aspect of user security in N4. As you work in N4, your session is active and available. If you stop working in N4 but do not log out, your session becomes inactive and after a pre-defined duration, your session must timeout to maintain the integrity of your session. By default session timeout is 20 minutes.
If your session has been inactive for a while,N4 displays a session timeout warning and allows you to either end or continue your session. If N4 does not receive any response from you before the session timeout period expires, it ends your session and logs you out to maintain the security of your account.
Also see:
Configure when a session timeout warning displays for the user to interact with the application.
Change the default session timeout duration.