I'm currently using the 30 day trial of Multiplicity KVM. So far the functionality has been great, and I'm quite certain that I will buy the software. However, there's one issue I've had several times, and I hope you could look into it.
Here's the scenario:
I have a desktop computer configured as a Primary in Multiplicity. Then I have two laptops configured as secondary computers on the left side of the Primary PC. One of these laptops is also configured in KVM mode which I use most often.
The issue comes when I'm using the laptop over KVM, and I enable VPN connection in the laptop (which momentarily breaks the LAN connection between the laptop and desktop), the mouse and keyboard stops sometimes (not always) working over the KVM but display/picture works always. During the mouse and keyboard outage, the picture works, but I cannot interact with the remote computer. All mouse and keyboard actions are ignored. It will work again when I reconnect the KVM. But I need to change the VPN state quite often during the day, and the issue also shows up several times a day. Multiplicity KVM works when VPN is either enabled or disabled. But the VPN connection state change sometimes breaks it.
EDIT: Both the Desktop and the Laptop using KVM are connected with Ethernet cable. WIFI is disabled on the KVM laptop.