I have been using Ubuntu 20.04 for as long as it's been available (used 18.04 prior). For a couple of years now, I have not had to play with my NVidia settings at all, and everything has been just fine.
Just recently my computer did one of it's routine updates, and now every time my computer boots up my second monitor resolution is set to something other than what it should be. In NVidia X Settings, it shows as being set to automatic resolution. It also no longer detects the monitor type (just shows DFP-0 when I click on Detect Displays). If I force it to what it should be (It's a 1920 x 1200 BenQ monitor) then it is just fine. Or at least it's just fine until the next reboot.
I am also unable to save the settings. I can click apply, and then the "Save to X Configuration File" button. It comes up with another window stating /etc/x11/xorg.conf (which I presume is the default setup file). I click save and no errors are reported. However when I click on the Quit button, I get asked "You have pending changes... Do you really want to quit?" Obviously I have to at some point, but it seems this useless NVidia tool is not saving the settings when it should.
I am running Ubuntu 20.04 Tried NVidia driver 4.35, and am currently running 450.51.06. GTX950 Card on I7 with 16GB RAM.
Update
I have tried swapping my monitors around, and find the fault follows the monitor. IE if I swap the cables around (one is DVI the other is HDMI) then the cable/port that was working stops, and vice versa.
This tends to imply a fault with the monitor itself, but this seems unlikely, as the monitor is running just fine. Has this been the experience with anybody else? IE have you seen a monitor that suddenly stops talking to the computer and fails to identify itself, but the screen is still running/visible?
Of course the alternative answer may well still be that this is an OS/Nvidia problem, that has suddenly decided to stop talking to this specific monitor for some reason.
Thanks guys.
