On the Windows 10 machine, launch the Xbox Console Companion app (which used to just be called Xbox) from the Windows Store. On the left, select Connections (you may need to hit the menu hamburger at the top to see it); on the pop-up you should see the name of the Xbox One on the same network. (I had to turn off my VPN to see it.) Once I clicked it, the app showed me what was playing on my Xbox downstairs. By connecting an Xbox controller to the Windows 10 PC, either wired or wireless, you can take control and start playing games right on the PC.