Hi..
1. Select Default Web Site > Properties > Home Directory > Application Settings > Configuration > Options.
2. Enable the session state time-out and set the Session timeout for 60 minutes.
3. Select Application Pools > DefaultAppPool > Properties.
4. From the Performance tab under Idle timeout, set Shutdown worker processes after being idle for a value higher than 20. The default session time-out setting on IIS is 20 minutes but it can be increased to a maximum of 24 hours or 1440 minutes.
Also, do the below settings :
1. Start IIS Manager.
2. Right click the web application and select properties.
3. Goto ASP.Net configuration and click Edit Configuration.
3. In the State Management tab, set the session timeout.
Please mark it as an answer/helpful if you find it as useful. Thanks, Satya Prakash Jugran