my title might not be very clear, but I'll explain my setup in more detail now.

We have several customers (companies) that need to be remotely supported. At these customers we have servers running with our software that needs to be serviced. These servers are (almost) never connected to the internet. For this we have multiple PC's running VPN clients. These PC's run a VNC server so our service engineers can login from their home laptop remotely to these PC's and connect from there to our customer via the VPN connection on the PC.

The problem is however that several customers do not allow split tunneling. That means that when we connect via VPN to such a customer the VNC connection drops. Our current workaround is using a Citrix VM which we control via XenCenter console, but it's quite slow.

Are there common solutions to handle this?