U4919DW, Network KVM software is for ever broken

I have a much appreciated U4919DW monitor connected via USB-C to a Dell XPS laptop and to a desktop computer via DisplayPort + USB.  I use a hotkey to switch between the two inputs and that works well.

• When running the laptop, I also have the laptop screen next to the main screen, with the two screens in "extend" mode.
• When running the laptop, I have second screen on the other side of the main screen, both screens also running in "extend" mode.

The problems start with the implementation of the KVM Network solution.

I can install and configure a cluster with both PCs, and it basically works in that I can move the mouse across all three screens in either KVM switch state.  However, when I toggle to the other PC, there is a several second delay where the system struggles to understand how things should work when I try to move the mouse across screen boundaries moving from one PC to the other.  Sometimes it takes some effort to encourage the mouse cursor back at all.

To make matters worse, when I give up and try and switch off the Network KVM feature, it has a habit of re-enabling itself.,  I seem at last to have sorted that out - it required me to actively remove the configured cluster.

This is all such a shame... the feature would be great to have, but is either so badly implemented as to be worthless, or perhaps I am misunderstanding how it should all be configured.