I'm using an old laptop running Xubuntu 20.04 as a server, which sits in a cupboard with the lid closed, using x0vncserver to access it remotely. Recently I had to reboot it, but when it came back up I couldn't control it via VNC. I could see the screen and move the mouse, but mouse clicks and keypresses were being ignored. Further investigation revealed that everything was fine until the screensaver kicked in -- no screensaver and everything is fine, but the moment the screensaver kicks in, it stops responding.
For the moment I've disabled the screensaver, which is not really a satisfactory solution. Can anyone suggest what the problem might be or what I might do to fix it?
Update: It isn't the screensaver. I disabled the screensaver but the screen still blanks after about 5 minutes (despite power settings saying do nothing when lid is closed, go to sleep never, and so on), and at that point I lose interactivity. It used to work fine until I rebooted the other day, and I have no idea what I might have done that would affect it.