Remote desktop server and client software
AnyDesk is free for private use and offers flexible license models for organizations.

To run: Menu -> Internet -> AnyDesk
To run in a terminal: anydesk

NOTE: If your system uses Wayland, it cannot accept incoming connections. If you cannot connect to this machine with AnyDesk, either disable Wayland or switch to RustDesk which actually works and is more secure.
On Raspberry Pi OS, Wayland can be disabled by running "sudo raspi-config" in a terminal and navigating to Advanced Options, where Wayland/X11 can be toggled.
Again, RustDesk is recommended. It's open source and works better.
