Windows – How to configure RealVNC Viewer to display on only specific monitors instead of all monitors

Try using xrdp to run your VNC session. You can specify the screen size when you open the session. When I first tried it, I found it wasn't stable, but recent releases seem very stable. See my experiences with Remote Desktops with VNC and RDP for some ideas.

UPDATE October, 2017: Windows 10 now natively supports screen savers on all monitors by default. I do not know what version this was implemented on, but I am running 1703 (Creators Update) and this is now the standard behavior for screensavers.

Original answer: The latest information I can find is that the screensavers in Windows 10 only support the primary monitor. Third party tools may allow for multi-monitor support, but it is not yet built-in.

Going back to the release of Windows 10 Microsoft was aware a few people wanted this capability, but not very many, and so they appear not to have made an effort to add this.

I'd suggest you open the Feedback app in Windows 10 and suggest this, or find if someone else has suggested it, and then try to get others to vote for it to raise its visibility and to let Microsoft know it's something people want.

Here's a discussion on the Microsoft support forums on this topic. It began in 2015, and has updates from 2016 as well: https://answers.microsoft.com/en-us/windows/forum/windows_10-start/no-multi-monitor-screensaver-support-in-windows-10/0ed8a245-97f8-4962-9caa-0776d9a8c4f2