When you're running a TN3270 application through the TN3270 service in Microsoft Host Integration Server 2010, the TN3270 session may stop running. When you try to re-establish the session, it starts to work again. When this issue occurs, you may see an instance of event 306 that resembles the following in the Application log:
Input from the client ::1 (port port_number) using LU LU_Name was ignored.