Win 7 VPN dropping every 20-25 minutes - How to Troubleshoot

We support many off site users who gain access to the internet in a variety of ways. We use Win7's built-in VPN.

If the user is at home we have them reboot their router and almost invariably that fixes the problem.

From time to time we get users who don't have a router or modem, but get their internet access from a hotel/motel or extended stay facility.

I have never been able to figure out how to help them. Is there something I could look for in the log or a change in the settings?

Any help would be greatly appreciated.

You might consider disabling some of the security settings in the GPO, Computer Configuration>Security Options.

The ones that disconnect client sessions after a certain amount of time are suspect but I can't say which ones will have an effect on your particular problem.