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I want to configure different scales for my 4K monitor and the FHD, but it looks an impossible challenge.

Next my different tests and conclusions. A lot of things are not working, so I need to know (to decide) what to try to fix first.

Could you advise me about which path to take to get it working?

One important note: 30Hz is not enough refresh ratio. After a few hours, my eyes are killing me.

Conclusion.

  • BUG? Thunderbolt 3 cannot handle 4K higher than 30Hz.
  • BUG? HDMI is not working in Wayland. The monitor detects the connection but goes to sleep mode (No signal. Entering in power saving mode).
  • BUG? In X11 the Scale option is shared between all displays.
  • Fact: Display management is the worst parts of Linux.

Specs.

  • SO -> Ubuntu 18.04.2 LTS
  • Kernel -> 4.18.0-16-generic
  • Drivers -> Nvidia 390.116
  • Laptop -> Dell G5 15
  • 4K -> LG27UD68P-B
  • FHD -> HP 2311x
  • Video -> GeForce GTX 1060 with Max-Q Design/PCIe/SSE2
  • Video lspci -> NVIDIA Corporation GP106M [GeForce GTX 1060 Mobile]
  • Thunderbolt 3 -> Intel Corporation JHL6340
  • Thunderbolt 3 to HDMI adapter -> https://www.amazon.com/Cable-Matters-Multiport-Adapter-Ethernet/dp/B01M0K0DL2

Test 1

  • X11
  • 1 shared Scale option
| Connector   | Display   | Resolution | Hz  |
| ----------- | --------- | ---------- | --- |
| Built-in    | Built-in  | 1920x1080  | 120 |
| HDMI        | 4K        | 3840x2160  | 60  |
| Thunderbolt | FHD       | 1920x1080  | 60  |

Test 2

  • X11
  • 1 shared Scale option
| Connector   | Display   | Resolution | Hz  |
| ----------- | --------- | ---------- | --- |
| Built-in    | Built-in  | 1920x1080  | 120 |
| HDMI        | FHD       | 1920x1080  | 60  |
| Thunderbolt | 4K        | 3840x2160  | 30  |

Test 3

  • Wayland
  • HDMI does not work
  • 2 shared Scale options
| Connector   | Display   | Resolution | Hz  |
| ----------- | --------- | ---------- | --- |
| Built-in    | Built-in  | 1920x1080  | 60  |
| HDMI        | NO SIGNAL |            |     |
| Thunderbolt | FHD       | 1920x1080  | 60  |

Test 4

  • Wayland
  • HDMI does not work
  • 2 shared Scale options but 4K is not scaling :)
| Connector   | Display   | Resolution | Hz  |
| ----------- | --------- | ---------- | --- |
| Built-in    | Built-in  | 1920x1080  | 60  |
| HDMI        | NO SIGNAL |            |     |
| Thunderbolt | 4K        | 3840x2160  | 30  |
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  • I don't actually see a question.
    – guiverc
    Mar 25, 2019 at 9:21
  • @angelcervera that's actually oh so normal. the whole point of wayland was to solve modern display problems. also what do you mean by HDMI does not work. like specifically for 4K or in general under wayland? is that hdmi cable 4k compliant?
    – tatsu
    Mar 25, 2019 at 9:27
  • @guiverc I highlighted the question. Mar 25, 2019 at 10:01
  • @tatsu 4 different tests, always using the same cable, same displays, etc. X11 detects the display connected to HDMI but Wayland is not. Mar 25, 2019 at 10:03
  • 1
    I really do. you can temportarilly create it as a dual boot, once you're done you can delete it a eat up the space it took back into your partition via gparted.
    – tatsu
    Mar 25, 2019 at 11:01

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