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P3421W USB hub seems to crash from time to time

Hello folks,

I have been using the P3421W since the start of April now. It is connected via USB uplink and DP to my private PC and via USB-C to my Lenovo Yoga 14s.

The following peripherals are connected to the display itself:

- Web-Cam
- Mouse
- Keyboard
- External DAC

When using my private PC connected via the USB uplink and DP I have no issues.

Only with the laptop which is being charged via usb-c from the display as well:
- I had to switch to a special USB-C cable to have my peripherals running without any issues (static noise when using the external DAC etc.)
- Now whenever I hook like a little USB-HUB-LAN connector to the display either the sound gets static again or my mouse would lag a lot. Ergo: The Display cannot handle more than 4 usb devices at the same time
- but even though since bying the new USB-C cable it works much better from time to time the USB-HUB seems to crash. For a split second my usb devices do not work anymore and then they come back up. The external DAC does not handle that too good since it takes a lot longer to come back or needs a cold restart itself and the display being unhooked from the laptop

Does anyone encounter the same problems with using all the USB ports (or even more via a small usb-hub)?

Thanks in advance for your help

Kind regards

Antworten (17)

Hey Immanuel,


I also do experience a problem with the USB Hub from the Dell P3421W. I got the monitor connected to my Macbook Pro via USB-C and into the monitor I've connected a Logitech Streamcam and a Focusrite Scarlett USB-Audio Interface.


What drives me crazy, is that sometimes when I turn the monitor on, my peripherals get powered but sometimes not. Sometimes I have to restart the monitor 10+ times, until my usb devices will turn on.. 

Somebody got any help on that issue? Thanks!



that sounds slightly worse than my situation. One thing that helped was buying a USB-IF certified USB-C cable. Before that it was a lot worse. But...it's still not perfect.

Kind regards



Hey guys,

I have the same problems. Did you get any help from Dell?

What else did you do?


Good morning.

No, even though they asked me a bunch of questions. But they never really responded to my lengthy answers. Really disappointing. How's your situation?



I got nearly same problem (but only with 2 devices connected) - I got so many issues with Dell P3421W and USB Hub crashing.. and always in combination with Lenovo notebooks (on my end T490s, T480s, T14s).
Everything is working and then from second to the other second my keyboard stuck during writing, or mouse has same problems or even it doesn´t work anymore. Then I also have to restart, shutdown, reinsert USB C, power off display, etc. like 30 times and then sometimes it work again and sometimes not.

I got normal USB keyboard and USB mouse connected to Dell display and the USB-C (original!) Dell cable connected to my Lenovo notebook which is charging fine, display is working fine - only massive problems with mouse/keyboard.

I tried already everything - drivers up to date on notebook, firmware display up to date, display driver installed on notebook, etc. - no solution until now.
The only workaround: we connect mouse & keyboard directly to notebook… but this is not what we want.

Did you got already a solution for your problem?



I had similar problems in the beginning. Buying a USB-IF certified USB-C cable helped. But with more than just a mouse and keyboard attached I still have problems from time to time. DELL already has swapped my monitor out for a new one from the same model but this did not help. They then advised my to turn to Lenovo support, since my laptop is a Lenovo (Yoga 14s ThinkBook).

But the Lenovo broke anyway and I am waiting for a replacement ^^


Hi everybody,


we´ve got the same problems with 10 of these displays in combination with 3 different dell laptops (Latitude 7400, 5400 and xps 17). I know that the U3419w had the same issues with the usb hub, for this model is a non public firmware available (M3B112) that´s fixing this issue.

Maybe Dell have a non public firmware for the P3421w too?!




same here. Have my Lenovo X390 conneted and loaded with USB-C and a wireless dongle for keyboard/mouse to internal USB-Hub. Until then I had only short interrupts. But when I connected a webcam to the Hub it went worse. Mouse/keyboard stuck all the time as well as the cam. When I use the cam, it works for around 30s and then gets disconnected. When typing, keys are supressed or send several times.

Installing new display firmware M2B205 did not improve anything.

Could anyone solve thisprobbbbbbbbbbbbbbbbbbb? (thats how it looks, when I do not correct  




Hi All, 

short information - we couldn´t solve that problem! I deeply investigated but there was no solution. We now use HDMI and mouse / keyboard directly connected to the display and then the USB cable for the hub connected to the notebook and extra power cable for the notebook. 
So instead of one cable to the notebook for everything we have now 3 cables. Not good but our user can at least work without problems...
I found something in the troubleshooting guide:
Note: Dell P3421W supports display over USB Type-C port with Alternate mode DP 1.4. Ensure that the USB Type-C on your PC supports Alternate mode DP 1.2 or above.
But I couldn´t find out what exactly Alternate Mode is and what the T14s is supporting. Maybe someone else here know that?


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