Why do I see warning messages about sessions disconnecting?
When any iOS App is sent to the background it is required to stop executing after a fixed period of time so that it does not drain your device battery or consume CPU time when it is not in focus*. This time limit is 10 minutes. As the time limit approaches, TTerm will warn you that it will soon be forced to stop executing and will disconnect your host connection just before that 10 minute time limit is reached. Tapping the notification will return you to TTerm and avert the disconnection.
You can avoid seeing these messages by keeping TTerm as the App running in the foreground whilst it is connected to a host.
You can disable these notification messages by opening the iPad Settings App, selecting notifications and selecting the TTerm item in the notification center.
*Several classes of application are exempt and permitted to run in the background by Apple. These include music playing apps, VoIP apps and Navigation Apps. Terminal emulators are not permitted to run in the background.