multi-monitor layout/detection not persistent (docking, displaylink, kde)

Hello,

• Context :

I have a dock labelled DisplayLink, 4HDMIorDP (actually DVI under the hood) to USB-C PD charging. So I use it with 4 external monitors and the internal monitor. I'm running Kubuntu20.04, on a laptop with an Intel iGPU and nVidia dGPU.

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• Problem :

When booting on with my dock plugged in, the external screens stay black.

Then, calling $ arandr GUI, I have to go to the "Outputs" tab, and activate each of the four DVI-I-M-N (M and N belonging to {2,3,4,5} and {1,2,3,4} respectively), by clicking the validate icon.

It then spawns all of them but in a mess, and I have to re-arrange them through the Display Configuration Utility in KDE ($ kcmshell5 kcm_kscreen CLI if one is too lazy to search for it in the app menu GUI).

But at each reboot it get back to the external blank screens.

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• Trials :

Previously on another machine I used to launch a bash script at each session startup, doing xrandr <my chosen arrangement>. However i'm not at this step yet, and I first would like to get all my screens active at each reboot.

Here or or