The IB Gateway (Build 976 or later) is configured to automatically log off each day at 11:45 PM local time for operational and performance purposes.
Clients can adjust the time at which it occurs each day by selecting the Configure and then Settings options from the IB Gateway menu followed by the Lock and Exit option from the Configuration pane. There you may adjust the HH:MM and AM/PM election for the Auto Logoff Timer.
Clients can also specify a time of day for the application to automatically restart (without authentication requirements) by selecting Auto restart. Please review auto-restart considerations before using this feature.