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U2419H daisy chain to P2419H, not extending
I'm trying to run three monitors driven from a Surface Book 3 via a Surface Dock 2. The dock has dual USB-C out for displays. I have one of the USB-C out from the dock going to a Dell P2419H. The second USB-C out on the dock is going to the DP in on a Dell U2419H and then I have the DP out from the U2419H going to the DP of another P2419H. The problem that I have is that the daisy chain only duplicates my middle monitor to the left monitor. The display settings are set to extend and my displays are extended between the middle monitor and the right monitor....but middle and left are duplicated. When I go into my display settings it only recognizes two monitors. The U2419H and the P2419H on the right. Display settings don't even recognize a third monitor on the left, yet the middle can duplicate to it. Thoughts?
CRCaldwell
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September 23rd, 2021 06:00
I was hoping that the included diagram with labeled monitors would have sorted out the whole "left monitor" versus "right monitor".
Anway, I verified that MST was enabled and then connected directly to the surface book. That worked. So initially I thought the dock simply didn't support it. However, I reconnected just that single DP cable to the dock so just the daisy chained monitors were connected via the dock and it worked! So then I connected the third monitor and it worked as well. Although the specs on the Surface Dock 2 say that the USB-C out ports are identical, the only thing different is that when I plugged both cables back into the dock, their positions were swapped. That or it all comes down to what order they are connected. Either way, your troubleshooting steps led to the solution I was looking for.
Thanks
jphughan
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September 23rd, 2021 06:00
@CRCaldwell So just to confirm, the displays that are cabled as a daisy chain are mirrored? You described your cabling setup and the models of your displays, but then switched to talking about left, middle, and right displays without clarifying which of your display models is in which position. Did you enable MST on the display that has another display daisy chained off of it? If so and you’re still seeing mirrored output and seeing Windows Display Settings showing that display pair as a single display rather than as two unique displays, then the Surface Dock 2’s outputs might not support DisplayPort MST output, which is necessary for running multiple displays from a single output. But just out of curiosity, try these tests:
jphughan
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September 23rd, 2021 07:00
@CRCaldwell Excellent! Unfortunately the diagram isn’t showing as of this writing. When users upload images, they are initially only visible to the user who uploaded them and to Dell moderators until they get approved for broader viewing, so right now I just see a little placeholder icon where that diagram is supposed to be. But glad you’ve got it working!