U2415, dual, WD15 dock, DP works, HDMI doesn't

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The HDMI cable that I use works fine by trying to connect directly from the U2415 to other laptop. 

Additional info. I've tried the advice from DELL-ChrisM by turning laptop and monitor off, unplug all the cables, turning them on again and plug the cables, didn't work. I've also tried to test the monitor using DP-mDP individually and they're both working, nothing wrong/defect with both monitors. The problem is only the one that connected with HDMI cable, detected but no visual.

@radenferdy  Building on my reply above, technically your setup SHOULD work too.  The only thing I can think of for why your display would be detected by Windows and even usable in the sense of app windows being draggable onto it without the display lighting up would be if that display was set set to the wrong input.  Did you check that?  If so, maybe try resetting that display to factory defaults?  That seems to clear up strange display issues sometimes.

@radenferdy  My wife has this exact hardware (XPS 13 9350, WD15, and 2x U2415s).  For her I daisy chained the U2415s together in order to have a single video cable connection to the dock and it worked fine.  You have to use DisplayPort or Mini-DisplayPort along the entire chain though, and make sure you use the DisplayPort output on Display #1 to feed the DisplayPort or Mini-DisplayPort input on Display #2.  Then you just have to enable DP 1.2/MST in the settings of Display #1. After that no further configuration was required on the system.

Hey, thanks for your response. 

Yes I forgot to mention that I also have it tested using daisy chain setup on How to Configure U2415 Monitor Daisy Chaining on Intel HD Graphics, but unfortunately it resulting the same symptoms. 

I've also have set the source to HDMI (MHL) 1, instead of DP, mDP, or HDMI (MHL)2. 

At this point how to perform factory reset to the monitor, because there's no such menu like when I successfully connect to laptop. Instead, whenever I press any menu buttons it only displays source selection.

@radenferdy  You might need to actually have the display showing an image rather than a "No signal" animation in order to access the full menu.  Can you try temporarily connecting your problematic display via the mDP output on the dock to see if it displays an image?  If so, try getting into the menu and performing a factory reset that way.

Hey jphughan,

Yup, I temporarily connected it to mDP and able to access the menu and perform factory reset. But problem persist. 

However, I tried again the daisy-chain method and both monitors display visual!

I believe the contributing factor to the solution of dual U2415 is ensure factory reset to the new monitor and daisy-chain both with DP-mDP cable (NOT HDMI). 

New Configurations:
1x U2145 (with DP1.2 disabled/terminal monitor) --> mDP out --> DP in --> another 1x U2145 (DP1.2 enabled) --> miniDP to WD15 --> USB-C --> Dell XPS13

Thanks for your help!

But still curious as to why HDMI to WD15 doesn't work. Waiting for official answer from Dell support.

Hi Dell-Cares,

That method in user manual only applies to monitor that successfully connect to a source (signal detected and visual is showing). 

I'm not sure if you're missed my explanation or otherwise I explained it poorly here. 

Bottom line is, that doesn't help.

Cheers.

@radenferdy  Glad you're sorted out, although I'm not sure why HDMI wouldn't work, and I don't think my wife would much appreciate me mucking around with her home office docking station setup given that it works at the moment and she needs it!

Just as a side note though, when describing a cabling strategy for displays via text, it makes a lot more sense to start with the system and work outward, since the system is the source of the video signal being transmitted outward, rather than starting at the end of the chain and working your way to the system.  You also mixed up the mDP out and DP in.  The U2415 only offers a DP out and an mDP in, and there's only one way to define "out" and "in" in this case since the video signal only ever travels in one direction.

Hi,

I hope you are well.

Shalvi here. Just checking if you got the chance to follow the steps shared. If yes, can you please share an update with me?

Awaiting your response.

Thanks.

@jphughan Yup, my bad on poorly describing the sequence of connection there. Thanks for the input and your pointer to the daisy chain setup. For now the monitors serve their purpose