Windows 7 VPN Stability

VPN Connects to remote network and stays connected for hours if I do not perform any function using the remote server.

However if I browse files, use VNC to manage server etc. it works but after a few minutes the VPN shows status of “No network access” and all the remote functionality stops working.

Searched net for solution but none appear to work so far.

Any suggestions.
I don’t belive it is anything to do with port forwarding or routers as functionality does work for a while i.e. it is not blocked.

Client config:
Windows 7
VPN IPv4 with use default gateway on remote network disabled

Remote Server (Windows 2003)
Behind Netgear router/firewall