Connecting a single monitor to the docking station at a time works just fine. Verified with both monitors and both DisplayPort connectors.
When I connect both monitors at the same time the Settings application i Gnome detects both correctly, but I am only able to get a picture on one, the other always stays black (not always the same though). Disabling the “built-in” monitor in the laptop changes nothing - one external monitor stays black.
Attaching both monitors directly to the laptop using USB-C actually allows me to use all three monitors (highest resolution) simultaneously without any problems.
I’ve also tried to attach the monitors to the 2x USB-C connectors in the docking station which does NOT work. The Settings application doesn’t even register the monitors, even though I do see some usb related stuff happening in dmesg.
How can I debug this (presumably docking station problem) further. I would prefer to make the monitors work with the docking station, but the second best thing is to be able to make a usable bug report.
This almost sounds like the laptop sees only one external monitor when attached to the docking station. When attached locally it actually sees and configures both.
Which monitor does it see in the docking station? The one attached first? The one attached second? Random if both attached when docked/booted?
We really need a bit more detail to fully identify the problem, such as laptop identification, docking station identification, etc.
The full output of “inxi -Fxx” when the laptop is not docked with both monitors attached, When it is docked with no monitors attached, and When it is docked with both monitors attached would help track down the issue.
I’ve come a bit further though. The problem seems to be related to all three monitors having been enabled at the same time.
The following workaround will make the two external monitors work (when the built-in monitor is disabled). Do these steps synchronously on both external monitors at the same time:
Set “Resolution” to 1920x1080.
Set “Resolution” to 3840x2160 and “Refresh Rate” to 29.56Hz
Set “Refresh Rate” to 60Hz
I’ve experienced that a monitor sometimes would contain a 1/4 (top left) part of the picture. Sometimes even the build-in monitor that was supposed to disabled while the external monitor that was supposed to have the picture would be blank. But I can’t seem to reproduce this behavior consistently.
Every time I undock the laptop the configuration gets buggered and I need to do the above 3 steps again.
All three monitors works fine at the same time using the USB-C ports directly in the laptop.