Terminal server disconnects every 56 minutes

I am using a vpn to remote desktop into a Terminal Server installed on Windows server 2003. Every 56 minutes +or- 1 minute I get the Microsoft message “Reconnecting”
“The connection has been lost attempting to reconnect to your session.”
The program that is open on the Terminal Server is still operating and all data is saved.
The connection returns within a few seconds. Is there a time-out setting on Terminal Server?
Or another time setting that I need to adjust?