Problem nokia 5800 - disconnect from WLAN while server in app is listening

[hasnain]

I am developing a app in QT for nokia which use WLAN network. i am using nokia 5800 as testing device . Nokia 5800 got some problem with its WLAN. I require phone to stay connected to WLAN all the time while application is running,because a i got a server in app which is listening on a port for incoming connections all the time, But phone disconnect from WLAN after a while server is started. Any ideas how to make phone stay connected to the WLAN or GPRS/EDGE all-- the time.