I recently installed Debian Stretch on a new server and it only shows the screen resolution of 800 x 600 under default primary when I run the xrandr command. I have tried adding other resolutions and I get failure errors. I am very new to linux and have no idea how to get this working any ideas. I have also tried installing a brand new graphics card hoping that it might fix things to no avail.
Welcome to our forums.
To solve your issue, please provide some more detailed information. For instance, you could paste the error messages you receive. You could also post the output of
xrandr without any parameters that should provide some insight about the system.