Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. The statement has been terminated

I have many users on my web site (20000-60000 per day), which is a download site for mobile files. I have remote access to my server (windows server 2008-R2).
I’ve received “Server is unavailable” errors before, but am now seeing a connection timeout error.

I’m not familiar with this – why does it occur and how can I fix it?

How does the session timeout work in IIS 7?

In web.config, I set timeout in the sessionState to 20 minutes. According to MSDN, this timeout specifies the number of minutes a session can be idle before it is abandoned. In IIS 7, DefaultWebSite->Session State->Cookie Settings->Time Out automatically is populated with timeout value set in web.config, which in my case is 20 minutes. Also, Application Pools->DefaultAppPool->Advanced Settings->idleTimeout, I set it to 10 minutes.