P2719HC, U2415, daisy chain

@oGeraldo  Your thread title says U2419HC, but your post says P2719HC.  Which display are you actually using?

Good catch! I split his question off of an older U2419HC thread, so most likely his is the P2719HC. When we get notice from him, I will fix titles.

@oGeraldo Actually I just realized that the P2719HC is just an FHD/1080p display, not a QHD/1440p display as is more common for 27" displays.  If it had been a 1440p display, that might have explained strange daisy chain behavior because your system wouldn't have had the bandwidth to run a QHD+FHD daisy chain and USB 3.x traffic all over a single USB-C connection.  But since it's just FHD, what you're doing should definitely work.  The only thing that I remembered reading about was this thread, where basically a user had the 24" version of your P2719HC and was trying to daisy chain it to a U2419HC.  For a reason that still isn't clear, the fix in that case was just to swap the order of the displays in the daisy chain.  There's no reason that should have been necessary, and I realize that isn't an ideal option in your case since the U2415 doesn't have a USB-C input, and therefore using it as the first display in the chain would prevent you from carrying video, USB data, and power over a single cable to your PC.  But I mention it in case this is another one of those irritating situations that seem to crop up in the tech world where things that SHOULD work don't always ACTUALLY work.

The only other thing I briefly considered was asking you to make sure you were in fact using the DP output on Display #1 and the DP input on Display #2, since I've helped others where they accidentally mixed those up.  But if you're able to get the expected setup for a few seconds, then cabling doesn't sound like your issue, unless it's a case of an actual bad cable somewhere.

On a side note though, if you just got a P2719HC you might want to rethink that model selection if you'll also be using a U2415.  The reason I say that is that you'll have a 27" FHD display next to a 24" FHD display.  The fact that both displays are the same resolution despite being a different physical size means that instead of the 27" display giving you additional workspace with that extra size, you'll instead just have a larger -- and grainier -- version of the same size workspace.  The difference in sharpness due to the reduced pixel density is likely to be even more noticeable when you've got a 24" FHD display right next to you to compare against.  If you only want an FHD-size workspace, you might do better to get a 24" USB-C FHD display for consistency.  If you want more space, then consider getting a 27" QHD display -- although if you go that route, you'll run into the bandwidth constraint I mentioned earlier.  One way to avoid that would to get either the U2719DC or U2721DE.  The latter has built-in wired Ethernet if that would be useful to you.  But they're helpful because they have a "USB-C Prioritization" option that allows you to customize how the USB-C link is setup.  The High Resolution option would allow you to maximize video bandwidth and therefore have enough to run QHD+FHD through a single cable -- with the tradeoff being that you'd only have USB 2.0 speeds available for whatever you plugged into the display's USB ports.  But depending on what you'd plug in, that might be fine.  Otherwise, if you have the USB-C link carry USB 3.x, you won't have enough bandwidth for QHD+FHD, so you'd have to connect each display directly to your system.  But some QHD USB-C displays don't offer this option at all.  They will always set up the USB-C link to support USB 3.x, which is why I mentioned those two U Series models that have this flexibility.

@jphughan thanks for spoting it,this is a typo. I am using the P2719HC (connected to my laptop), and the U2415.

@jphugan @DELL-Chris M Thanks a lot for your very clear reply, it is much apreciated. I cannot return my U2415, so I will return my P2719HC, and look to get one of the monitor you recommended (U2719DC or U2721DE)...if I manage to first resolve the other issues I get with my new XPS 15 (Video freezing, SupportAssist bugging+enable to update+raising a Hardware issue). I onl;y plug in my keyboard, mouse and printer, so I guess USB 2.0 will be fine with either U2719DC or U2721DE. I agree with you, "in the tech world things that SHOULD work don't always ACTUALLY work". Although unfortunately this happen all together with the Dell products I just purchased. Hopefully, I will find a resolution for all issues.

Hi,

I see that you're working with our technical support team. We'll keep track of this from our end and keep you posted.

-Gautam.