I've got a strange problem with our terminal servers. Here in the office we run two terminal servers that both employees inside the office at their workstations and outside the office at home and abroad connect to for work.
A user connected to a remote session on the terminal server from a workstation inside the same LAN can stay connected indefinitely until he/she terminates the connection, even if they sit idle for a while (which is how it should be).
However, it's a different story for users connecting from the outside WAN world. A WAN terminal server connection will be automatically terminated if they sit idle for a few minutes.
I tested this by moving my computer from inside our LAN to a DMZ, connecting it to an extra port on the router and thus going around the LAN so it's seen as a box from the WAN. Sure enough, my terminal services connection died after I sat idle for a few minutes. Rejoined the LAN, and it stayed connected indefinitely.
So what could cause this difference between WAN and LAN terminal services connections? How can I change things so that a user from the WAN can stay connected to our terminal servers without being booted for idle time?