My relationship with Mouse Without Borders is complicated. On the one hand I dearly love it and rely on it for a lot of my workday. On the other hand it stops working for various reasons and it drives me absolutely insane. I have used Synergy in the past with Linux and MacOS, but if you are just connecting Windows machines, MWoB is the way to go.
The reasons to love MWoB are numerous. It lets you use one keyboard and mouse to control multiple computers. This is different than using a KVM switch because there is no video involved. Instead, you place up to 4 computers side by side and MWoB lets you move the mouse off of the screen on one machine and onto the screen of another. This is significant if you use several machines at once. Most video setups support 1 or 2 monitors, but I am hardcore and like to use 3 or more screens at the same time. I like to pretend that I work at NASA.
The reason to hate MWoB is that it sits at the intersection of two explosive elements: human interface devices and Windows network security.
The keyboard and mouse are the human interface to a computer system. They are of tremendous psychological significance to the human operating said computer. If the human interface malfunctions in any way, the emotional impact on the human is swift and severe. Keyboard and mouse malfunctions are Hulk-level rage inducing. This really isn’t MWoB’s fault, but it did decided to play a dangerous game.
MWoB uses networking to connect two Windows systems together. This means that MWoB is at the tender mercy of Windows Defender, a fickle beast. Windows networking can make file shares randomly disappear; it can quit seeing print queues; it’s utter chaos. I really dread messing with firewall rules on Unix systems, but I actively avoid it on Windows. The same goes for editing Group Policy. You can spend hours tuning both just to see a Windows security update wipe all of it out. Using MWoB means you have to get two Windows systems to play nicely with each other reliably, no small task. That’s two Windows operating systems, two MWoB installs, and two panicky firewalls to appease. I have reinstalled Windows on more than one occasion just to realize that the problem that I am having is actually with the *other* computer. Sure, Windows systems and networks are easy to set up, but like a house made of sticks, they’re easy to knock down. Again, this isn’t necessarily MWoB’s fault, but it’s a piece of software that has decided to play a [doubly] dangerous game.
When you force a vital computing component like your keyboard to operate in a volatile environment like Windows networking, you get a service that alleviates a tremendous strain. However, the sudden re-introduction of that strain is is eye-gougingly frustrating.