M3 Macbook Pro and Dell U3419W Display not working with USB-C/ Thunderbolt 4....sometimes...

I am having this trouble too with my M3 Max Macbook. I've used this monitor for several years with my last MBP (intel based) and throughout a day there are a couple times I have to plug and unplug the monitor. On my new M3 MBP the monitor doesn't come back, just "scanning for signal". I have to restart the M3 MBP to have it see the monitor again.

Also, I have a web cam connected to the USB of the monitor. So far I've not been able to get that USB camera to show up on the M3 MBP. It does just fine in the Intel MBP.

The whole "you're doing it wrong" attitude with Apple hardware only goes so far. All cables I've tried have been 1 meter. Additionally, my 2020 intel, and my M1 laptop, that are all running 14.4.1, have no issue with this display, even with a longer cable.

To use a USB-C connection to high resolution display like this one, the USB-C cable needs to be ONE meter or shorter.

Longer cables could create transmit errors due to signal deterioration. RECENT versions of MacOS will reduce the resolution or blank the display. Older versions of MacOS may tolerate the errors and seem to just work, with imperfections so minor and random that may not be detectable to the naked eye.

The Apple standard for its built-in hardware-accelerated displays, makes them suitable for full-motion video for production/display of cinema-quality video with NO dropped frames, and NO dropouts or partial-blank scan lines for any reason.

Thanks. Good to understand the scenarios when the query is sent but out of all the 4 only the restart scenario worked consistently and 3 other scenarios are failing consistently. My old mac was used to work absolutely fine in all scenarios. With M3 , i always had to restart to get the display on to my monitor.

This has been an ongoing issue for me as well. I've tried the following:

• Updating the firmware for the 3419W (M3B103)
• Confirming the M3 is at the latest OS (14.4.1)
• Swapping out the Thunderbolt 3 cable for one that works on other monitors with the M3 laptop.
• Calling Apple Support (They implied an outright hardware incompatibility)

None of those things helped. What DID work, however, was a docking station. The problem there, though, is that the refresh rate is not great. That could be the quality of the docking station itself, however.

I wish Apple provided that (use only appropriately short cables) guidance directly, but they have not yet done so.

If you are already doing that, then that's one item off the suspects list.

And today the USB web cam attached that is attached to the monitor's usb ports is now working. Not sure if it was because of reboots all around or not.

I'm still swapping the monitor from a port on the left side (my preferred) to the port on the right (or vice-versa) when I come back and the system is sleeping.

I don't want to pull the "I've worked in IT for 20 years" card, but I've eliminated all possible factors I can think of. I am totally ok with using a docking station that can get around this issue. I just wish apple would be more transparent and just say "We made a hardware change and your monitor from 2016 no longer works with our hardware. Buy something newer, this isn't Windows."

I agree. I've got a two foot cable, found this one to work best a couple years ago after buying a couple different ones on Amazon. My previous Macs have worked fine with this monitor. It was only since I changed to my M3 MBP that my monitor started doing this odd dance.

So odd.

If I have a video playing or Spotify playing and walk away and computer goes to sleep, it usually wakes up just fine with the monitor. If I don't, I have to go through a dance of changing the cable on a couple different ports and waiting and then monitor comes back. Sure does feel like something that is related to software/firmware and not just a hardware issue. This really leads me to think it is something in the latest generation and can be solved with someone looking into the bug. It is repeatable.

I had this problem as well, and then figured it out via a tip in a different Reddit conversation - I get the monitor working when a) unplugging the laptop from the power supply and then b) plugging in the USB-C connector into the laptop. The laptop then charges via the monitor... hope that works for others as well, good luck!

The Mac does not rely on windows-like side-loaded "Drivers" which are actually packages of resolutions and settings for a specific display. Instead, it goes straight to the immutable source -- it asks the display itself.

To get a Mac display to become active, you need the Mac to query the display, and the display to answer with its name and capabilities. Otherwise, the display will not be shown as present, and no data will be sent to the display. "No signal detected" is generated by the DISPLAY, not by the Mac.

This query is only sent at certain times:

• at startup

• at wake from sleep — so momentarily sleeping and waking your Mac may work

• at insertion of the Mac-end of the display-cable, provided everything on that cable is ready-to-go

• hold the Option key while you click on the (Detect Display) button that will appear in Displays preferences (from another display)

so try doing some of those things and see if the display comes alive.

Agree, this is good to know.

And I also agree it doesn't seem to resolve my issues.

On wake up, the monitor doesn't come back, unless I have audio playing, like on Spotify, when it went to sleep.

I've tried doing monitor identifying, and that doesn't hasn't helped.

The only way I can resolve this is to reboot, which is not what I want to do every time I come back to my computer, or to plug/unplug the cable to multiple USB-C ports on my MBP. After a few tries it works. Though recently I also saw a message on the monitor indicating no USBC signal was detected. This was a bit different than before.

I contend that there is something different in my M3 MBP as I never had this problem on my older MBPs (and still don't, when I pull them out and plug in).

So I just came back from lunch. Computer and display were asleep. I woke the computer but the display didn't wake and screen wasn't extended. I turned off the display and back on, no extension. I unplugged and plugged back into the same port, screen didn't extend. I unplugged and plugged into a different USB C port on the MBP and the screen DID extend. Though I note it is different wallpapers than what I had set odd.

And still no luck getting USB devices plugged into the monitor to be recognized.

Thus far, no, I've not heard or had a resolution. Here is what I know.

When I come back from the computer/monitor going to sleep, I switch my USB C cord between the three USB C ports on my laptop and the monitor will eventually come alive.

I also found that if I leave music running, like Spotify, and then come back the computer and monitor will wake up just fine. Strange. Seems like surely this would be easy to figure out and resolve.

Hi there, anyone got this solved? just bought my new M3 and it is not working with my Dell U3419W.

Thank you