ASP._global_asax : System.Net.WebException: The operation has timed out

I know there are a lot of question regarding this. But please give me a seconds on my problem. My web application is returning an error The operation has timed out when simply saving a record in database. This works in other server. It happens that my web application is deployed in a cluster (web farms). My question is, why is occurs when my web is deployed in a web farm? And where is this problem occur? On IIS or Databse server?

Thank you so much