VPN over WAN?

Hi - I have a customer who has a private adsl between their office and a few hosted servers.. creating a WAN.

I support them for an application which is on one of the servers, with it's SQL database on another server.

The application is installed locally on their workstations but accesses the 2 servers for data and permissions for the application.

They are experiencing a problem where after 11 minutes of inactivity in the application it freezes....

We ourselves use the same version of the application but rather than a private adsl we use a VPN- without issue.

I am told by the customers IT support that they cannot use VPNs... okay.

It would be great to get some independant verification for this.

I am surprised they cannot simply allow VPNs on the WAN router at their office and the same at the data centre - then for the clients to log in via their workstations every day.

This may seem like a step backwards... it may cause their application traffic to leave the data centre only to come back again but it would at least allow them to use the application without freezing every ten minutes!