How can I use a single monitor when connecting to a multi monitor machine using Screen Sharing, VNC or RDP?
A simple solution that works for me is to

turn on &quot;Display Mirroring&quot; as soon as I connect
view my remote connection on a single monitor.

You can do this:

manually by going to &quot;System Preferences | Displays&quot;, and toggling it
or you can use this free opensource command line app to toggle it super easy from the command line.