Need Help! - Timeout Error [on hold]

We are currently working on java based project deployed on tomcat server and users connect to the website through IIS. IIS to Tomcat is connected using Boncode Apache tomcat connector.

We are facing timeout error even after changing the timeout values in IIS and Tomcat. timeout happens after every 20 minutes from client side where as server is still running.

Any guidance from you will be really helpful.

Error is:

Server Error in '/' Application. Request timed out. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Web.HttpException: Request timed out.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[HttpException (0x80004005): Request timed out.]