Nomachine無法控制Ubuntu Server解法

1. 無螢幕的Server(Headless server)並且有顯卡，登入後螢幕是黑的
   https://kb.nomachine.com/AR03P00973 根據步驟1的做法

sudo systemctl stop display-manager
sudo /etc/NX/nxserver --restart

參考:
https://forum.nomachine.com/topic/problems-connecting-with-nomachine-in-pc-client-without-monitor