Howto increase timeout of the server when generating BI report in portal?

Hello,

We have a very large BI report which we are exporting to excel from the portal.

Because this report is very large it takes a lot of time to proccess it and normally after a while the user receives this type of error:

500 Connection timed out

-

Error: -5

Version: 7000

Component: ICM

Date/Time: Tue Apr 24 10:30:04 2007

Module: icxxthr.c

Line: 2646

Server: <Server_Name>

Error Tag: {-}

Detail: Connection to partner timed out after 900s

My question is: How can I increase this timeout?