We have some shared devices used for testing and access to test-webservers are via a OpenVPN connection. But unfortunately people forget to disconnect and the device gets picked up by someone else and ... ok, you already got the point

Are there any way to make the devices automatically disconnect when they enter sleep mode or are locked? Right now it just reconnects when the device is resumed. Timeout on the VPN connection doesn't work, we need keepalive active for other devices :/
/Anders