How to simulate a windows second monitor

Question

edit: to simplify (for future reference), what I was searching for was a keyboard & mouse sharing software. See my answers for my findings.

I have a laptop that I use to connect to a VPN and remote desktops.

But I also recently bought a new computer, with its own monitor. But I don't want to connect to the VPN with this one, since the VPN connection is pretty poor.

What I wanted to do was to connect from the new computer to the laptop with mstsc.exe, and from there connect (with mstsc.exe as well) to my remote desktops. But the nested mstsc crashes.

Since I couldn't fix this issue, I tried to search for another solution, which would be to use TeamViewer or another similar software to connect to the laptop.

This works, but it's really bothering me to have these two monitors (new one + laptop's) and only use one (not even taking into account the very small resolution of the laptop's).

So what I'd want to do is be able to have a "fake" monitor, in which I would place my TeamViewer window. This way, I would be able to switch from my monitor to my laptop's screen seemingly as if the laptop was a second monitor, and keep my internet connection good on the computer.

How can I achieve that? I stumbled upon a few answers that said to go to the display settings, detect new screen and force adding a VGA monitor, but I can't seem to do that in Windows 10 (no such option appear after pressing "Detect").

Thanks for your help, and sorry for the wall of text, I wanted to be thorough.

Answer 1

I found a solution in the form of Microsoft Garage's Mouse Without Borders.

It allows to seamlessly share your mouse and keyboard between multiple computers.

I originally went with Input Director, but it uses UDP as a communication protocol, and that tended to lost the connection quite often, forcing me to restart it on the slave machine.

Mouse W/O Borders works perfectly.