Multiple displays with Dell docking stations
This question was asked and effectively answered a few months ago at https://discussions.apple.com/thread/251792108 , but it seems that the Dell WD15 or K17A dock with 2 Dell monitors (on MiniDP and DVI ports) that works fine with my Dell laptop, does not work properly when I plug in the USB-C cable to my MacBook Thunderbolt 3 port. After lots of experimentation and trying different cables it seems just using the MiniDP port the monitor goes into power-saving mode (i.e. no signal), and just using the DVI the picture looks kinda bad and keeps blinking at me. Plugging them both in has the same effect.
Documentation for the dock is at https://www.dell.com/support/home/en-us/product-support/product/dell-dock-wd15/docs and it seems that from the previous thread that Dell no longer supports MacOS. I just upgraded to Big Sur 11.1. How does one troubleshoot this to find the exact problem?
From the screenshot you can see that only one screen is detected, and it's as if the 2 external monitors are mirrored. I looked at the Color profile and noticed there are two of them, even if there is only one monitor connected. I have tried deleting either of the profiles but that doesn't seem to change anything.
Maybe there's a Dell BIOS update that can be applied if I find a Windows machine to download and install the Dell updates?
I bought an adapter for Thunderbolt3 to 2 DisplayPort monitors, and for cables I used DP to DP and DP to DVI. That didn't work (one of the monitors were either flashing or no signal). I had to use both DP to DP cables for it to work. So it seems the MacBook cannot handle a mixture of DP and DVI? I am not able to try TB3 to DP to DP on one side and TB3 to something to DVI on the other side yet (mbpro has 2 TB3 buses?) as I don't have the many adapters and cables to experiment. But it seems like something could be fixed with a software update by Apple or Dell if I were able to identify exactly what the problem is.
[Image Edited by Moderator to Remove Personal Information]
