NoMachine is designed to work out-of-the-box on headless machines on all supported platforms. On Linux a desktop environment must be installed.

Nevertheless, in some cases users can get only a small screen resolution without the possibility to change it ('stuck resolution').  This depends on the GPU which makes available only one resolution when the monitor is not present.

A common solution is to adopt a fake display dongle (also called 'dummy dongle') inserted in the video card port to simulate the presence of a screen and force the system to take full advantage of the GPU as if a real monitor is connected.

If the remote host is Linux, there are other alternative solutions, please see https://kb.nomachine.com/AR03P00973.