U2417H, loses signal when MST is enabled?

Question

Hello Dell Community! I hope you like to read. Because you're in for a treat.

I have two Dell U2417H monitors that support MST. I have daisy chained one to the other and I use the built-in Intel UHD 630 GPU. I have no dedicated graphics card. From the PC to the first monitor, I use a DP to mDP cable (extra long, purchased separately), and from the first monitor to the second monitor I use another DP to mDP cable (provided with the monitor). I have used this setup for a few years now, but not without issues.

Monitor 1: Dell U2417H
Monitor 2: Dell U2417H
GPU: Intel UHD 630
OS: Windows 10

Do I have to enable MST on the first monitor to get a signal to the second monitor? I recall having to enable MST on the first monitor when I first built this PC a few years ago (2017 I think). Now when I try connecting the second monitor with MST disabled on the first monitor I still get a signal, but it just mirrors whatever the first monitor is displaying (i.e. if you previously had extended desktop with two monitors it will now appear as duplicated desktop). Is this normal with MST I wonder?

The issue I'm having now is that when I enable MST on the first monitor, the signal is lost on that monitor and I'm stuck without signal, but the second monitor gets the signal. So the second monitor is getting signal from the first monitor but the first monitor itself is not having any signal. Which is very weird! This is the first time I have been able to pin the issue to the first monitor and MST. Although I have had issues with this whole setup right from the start all those years ago where Windows would for some reason start treating the second monitor as the main monitor, with the start menu and desktop icons appearing on that one as opposed to the first monitor. That was sorted out by reinstalling Windows. Now it seems I'm approaching that time of the year again where I have to reinstall Windows to get a working monitor setup.

As you can tell I can't tell head and tail on this. It's not a straight forward issue, and I'm starting to hate MST, and I'm starting to believe that I have a bad monitor.

Is there a way to tell what firmware version is in a Dell monitor? Is it possible to get an update?

I've been using this setup without any issues for the last year or so when I reinstalled Windows. Last evening however the PC went to sleep as I was busy watching TV, and when I woke it up, there was a blank screen on the first monitor (no signal) and a dimmed gray background on the second monitor (we got signal, but no picture). It's meant to display the lock screen and Windows login screen but there was none. The only way to log in was to use Remote Desktop from a second PC in the house. I tried rebooting the remote PC that way and then log onto it locally but I ended up with the same issue. I tried powering off and on again. That didn't help either. But I noticed that the UEFI POST screen was appearing on the second monitor! It had always been on the first monitor up until last evening. I even saw the Windows animation during boot, but nothing after that, no login screen. So it's not just Windows, but UEFI too was affected. This was before I was able to pin it down to MST on the first monitor. I then noticed I could drag the mouse cursor over to the second monitor, a definite sign that at least the second monitor was getting a signal.

I now have a method for getting "unstuck" from the MST setting on the first monitor. I connect it with a HDMI cable straight to the PC and then disable the setting. You can't actually get a working menu for changing settings on these Dell monitors unless you have a signal! Which is... wow! Mind-boggling! All you get to do is change input source in that little menu if you have no signal. What is Dell thinking?

I actually have newer Dell U2419H monitor connected to a second PC. I tried connecting that up as the first monitor to the issue PC and I got a signal straight away. I then tried daisy chaining it to the second monitor and enabling MST does not leave the first monitor without signal, which is unlike what I saw previously with the U2417H as the main monitor.

rnd42 · Accepted Answer

I no longer need help with this issue. I have fixed the issue myself. I don't know how, and I haven't been able to pinpoint the exact cause but I know for sure now that MST is involved somehow. A complete write up of my findings can be found at Linus Tech Tips forums at the following address.

https://linustechtips.com/topic/1417576-troubleshooting-mst-on-dell-u2417h/#comment-15301386

DELL-Chris M · Answer

The DELL-Cares virtual agent is required to ask all users for the private Dell PC or Dell Monitor Service Tag number to check the purchased warranty dates. 'extra long, purchased separately'. Dell only validated the provided 6ft cables. We cannot troubleshoot if you are using longer cabling. Reconfigure the physical setup and test like this = * PC DP out port --> #1 U2417H DP to mDP cable --> #1 U2417H mDP in port (Menu- Display- MST ON)* #1 U2417H DP out port --> #2 U2417H DP to mDP cable --> #2 U2417H mDP in port (Menu- Display- MST OFF)

rnd42 · Answer

I do in fact have warranty left on both of these affected monitors – I have warranty left on all five Dell monitors that are in my home. UltraSharp monitors come with a 3 year warranty. I have about two weeks left on one of the affected monitors and another four weeks on the second one. But I did not ask for official Dell technical support, and I should not be "required" to provide you with service tag numbers. If I wanted that, I would have called you. That's why I came to the "Dell Community": I don't want or need to make it official and ask Dell itself for help.

For readers that find it hard to understand what this is about, I opposed the automated messages that kept coming right after I started this topic. For context, here is the first private message I received from "DELL-Cares".

"Hello, I’m your Dell virtual assistant. I see you've opened a thread.

In order for me to review your system configuration, may I have the Service Tag / Express Service Code/ Order Number?

Refer the below link to find the Service Tag: https://youtu.be/xxISMlXqyVQ "

I received 7 messages from this robot, including the request to do a survey. I have put him (it?) on the ignore list (there is no blocking it seems).

I have tested connecting the PC with a Dell supplied DP to DP cable to connect my U2419H as the first monitor in the chain, and then from there, I have connected another Dell supplied DP to mDP cable to connect to the second U2417H as the second monitor in the chain.

This is a part number of a Dell DP to mDP cable: 05VX0-CA10-879

This is another Dell part number (DP to DP cable): 5K1FN15501HT1739

rnd42 · Answer

'This reply was marked as spam and has been removed. If you believe this is an error, submit an abuse report.' That's just great. That's the missing 'solution' post if you can't see it (unless it gets unblocked later on). As I was saying... you can find my complete write up on this issue over at Linus Tech Tips forums (with pretty pictures and everything). I use the same nickname as I do here. Just look me up or do a search for 'U2417H'. I will be leaving now. Have a nice day!

Monitors

U2417H, loses signal when MST is enabled?

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