[NAME]  You say you tried "both options", but I suggested trying the DP outputs individually, trying an HDMI output, and trying one or both USB-C outputs on the back of the dock, either individually or while another display is connected to another output.  I also suggested verifying that MST was enabled in the settings of the displays themselves.  So when you say "both options", I don't know what you actually tried.  As a general bit of advice, the more specific you can be about exactly what you're doing, the more likely you'll be able to get helpful responses.The WD15 when paired with your system would not have enough bandwidth to run dual 1440p 60 Hz displays.  It would only run dual 1080p 60 Hz or single 1440p 60 Hz.  The WD15 is also a regular USB-C dock, not a Thunderbolt dock like the WD19TBS.  And on the XPS 15 9575, only the USB-C ports on the left side support Thunderbolt.  The ports on the right only support regular USB-C.  The WD19TBS will operate in USB-C backward compatibility mode, but only at reduced functionality equivalent to the WD15.  So if you're using ports on the right and can only get a single 1440p 60 Hz display running, that's probably why.  Getting the WD19TBS connected to a Thunderbolt port on your system would allow it to tap into 4x more video bandwidth than running it in regular USB-C mode as it sounds like you're doing.But if the ports on the left aren't working, then I'm not sure what to tell you.  Does the dock show up in the Thunderbolt application?  Do you have your Thunderbolt drivers installed?  Are you running the latest system BIOS and TB3 controller firmware?  Is the dock running the latest firmware?  If you can't get the dock to work at all on your Thunderbolt ports, there may be a hardware problem with your system.I seriously doubt Windows 11 is relevant here.  Despite the name change, Windows 11 is not much more than a new feature release of Windows 10.  The fact that it the dock may not have been officially certified for Windows 11 doesn't mean it wouldn't work.  And if mass failures WD19TBS were occurring as users updated to Windows 11, I would expect we'd have heard about it by now.
I have recently purchased the DELL WDTBS docking station for my xps 9575 laptop. The 2 monitors I am using: P2421DC Issue is that I cannot get both monitors to work in extended display. The only way I have managed to get both monitors working via the docking station is via MST, but that does not support an extended display. Currently I have both monitors plugged in via the 2 Display Ports in the docking station, however only 1 monitor is detected. Further to mention I have already installed the appropriate recommended driver updates.  Having read up on the knowledge base I still cannot find the solution.   Please help me out. Thansk in advance  
Extended display option for multiple monitors not working with WDTBS docking 
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