Correct external screen resolution is not detected on Ubuntu 20.04

I have the following problem: when I connect an external monitor which allows for resolution 3440 x 1440, it is not detected. Instead, 1280 x 800 is maximum available resolution, although occasionally I get 1600 x 1080 or 2560 x 1080 as max. When I run Ubuntu on Wayland with Intel graphics, correct resolution is detected. I tried to insert modeline generated by running cvt 3440 1440, but it does not help, the monitor simply goes black.

Some information:

  • Laptop: Samsung NP940Z5L
  • External monitor: Samsung LC34H890WJI, connected by HDMI
  • OS: Ubuntu 20.04
  • Graphics: GeForce GTX 950M/PCIe/SSE2
  • NVIDIA driver version: 455.28

I would appreciate any help with this matter.

nvidia-bug-report.log.gz (354.1 KB)