Can you shed some light specific circumstances that have triggered this error, as it can be fired by a variety of different client issues. Do your clients run any kind of client side firewall or anti-virus/spyware?
The troubleshooting guide defines nc.windows.app.23712 as being triggered when the client is disconnected from the secure gateway because of a failure in the clientÕs configuration. It is possible a network adapter or other piece of hardware failed. The recommended action is to click "Yes" to re-establish your connection to the secure gateway. Click "No" to close the etwork Connect client. If you are still having trouble, contact your system administrator and verify your computerÕs system configuration before signing in to the secure gateway and launching Network Connect again. You can also try uninstalling and reinstalling Network Connect.
I would recommend contacting your system administrator, assuming this is not you , and monitoring the IVE logs while you attempt to connect.