U2725QE USB hub recognized as 2.0 when connected to MacBook Pro

Here are some follow-up results on the problem where the U2725QE monitor provides only USB2 speeds (at best) when connected to a Mac by Thunderbolt:

1. To clear the problem, the monitor needs to be started (or restarted) after the Mac has begun loading the OS. 
2. Simply cycling the power button on the back of the monitor, with a pause for 6-8 seconds, will clear the problem. Devices would have to be unmounted manually (‘Ejected’ in Apple-speak).
3. Turning on MST (Multi-Stream Transport) restarts the monitor, just like power cycling. As some contributors here have noted, the effect is temporary and only lasts until the next restart of the computer. Again, devices would have to be unmounted manually. 
4. To demonstrate that MST is no solution to the problem beyond restarting the monitor, note that turning MST from on to off has exactly the same effect as turning it from off to on.
5. The advantage of clearing the problem by restarting the Mac and power cycling the monitor during the restart (as I suggested in an earlier post) is that the OS will unmount the devices and otherwise tidy up before the restart.
6. The additional advantage from a cold start of turning on the computer first and then the monitor after the startup chime is that no additional starts or restarts are needed.
7. The problem does not occur when connecting the monitor by HDMI or DisplayPort, with the USB connection made through the USB upstream port. But that, of course, defeats the objective of a single-cable connection.

I’m still looking to Dell for a proper solution.

UPDATE - I was wrong!!!, the MST has nothing to do with USB-2/3/4. The problem is the link negotiation and it doesn't work well with Mac when monitor is already powered on OR in standby. The only workaround for now is to recycle monitor power when the Mac is online. I have reported the issue on Dell Support as well, but no luck even after months of struggling. Looks like it's macOS issue, because Windows Machine is negotiating the link properly during boot time. When macOS boots up it's not discovering monitor's USB capabilities over thunderbolt.

The USB failure of the U2725QE is not a MacOS or Apple hardware problem. I replicated the problem with the monitor connected through a Hewlett Packard TB3 hub. As with direct connection, everything works fine after the monitor is power cycled, including USB3 speeds. But if the hub is started with the monitor already powered on, nothing on the monitor's USB bus works at all - not even at the USB2 speeds of the direct connection. This last difference may be due to having TB3 rather than TB4 as the connection protocol.

I would have preferred to run this test using a Windows computer equipped with TB, to completely remove Apple devices from the chain, but I don’t have access to one.

I don’t know what other users have been told, but Dell Australia has said that a firmware update for the U2725QE is expected "around the end of August". I didn't expressly check that the USB problem was being addressed in the update, because my monitor has other problems that I was trying to fix. The kicker for many Mac users may be that Dell's firmware loader will require a Windows computer, I'm told.

Yes this setting is on the display itself. Click the joystick on the back, then toggle up for the full menu. Scroll down to the "Display" section and you'll find the MST option there.

Good luck! It didn't help for me, unfortunately.

[Edited by Moderator]

<< My resosolution, hertz, main display were not being remembered >>

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)

NB > Be sure you are running your experiments accordingly.

Just finished with Appler Senior Tech support and also with dell tech support, Appple MacOS doesnt support MST and I was advised to turned it back off.

Recap on my setup and issue:

• Macbook Pro M2 Max + 2 x U2725QE via Daisychain with thunderbolt 4 cables (supplied by dell)
• Hub is fickle and will connect as 2.0 or 3.2 depending on the connection or restart or power on sequence.
• My reosltuion, hertz, main deisplay were not being remembered and have seem to have stabilised by turning off MST on both monitors.

This is without a doubt a Dell issue. The hubs deep inside the DISPLAY are using this slow data rate, not anything inside your Mac. They are driven by Dell firmware.

[in my opinion] the Dell representative who suggested 'make sure your Mac is getting enough power' did not understand that the Ethernet adapter and the Hubs that drive it are ALL inside the DISPLAY, not inside your Mac.

The suggestion to check that your Mac is getting enough power reveals this lack of understanding (or lack of paying attention). This suggest to me that you need someone with a deeper understanding. You likely need a senior technician from Dell to review this.

The answer from any Apple official support you contact will likely be: "This hardware is inside a third-party device, is NOT running Apple software, and Apple does not provide Direct support for third-party hardware.

--------

Believe in yourself. You are on the right track. Be polite and professional, but insist that they treat your concerns seriously. Their response to date does not suggest they even listened or understood your concerns -- they assumed this was an Apple hardware malfunction.

Hi All

After dealing with Dell tech support that have told me its an Apple issue adn i need to raise with their support. I think i have multiple issues that steam from it being 2 x u2725qe via thunderbolt daisy chain. I will keep everyone updated once i get a ticket raised and i will create a specific thread for those issues.

I have a new Dell U2725QE monitor connected by Thunderbolt to a M4 Mac Mini running MacOS 15.5. I experience exactly the same problem where the USB bus on the monitor sometimes provides only USB2 speeds (and occasionally fails to connect a USB device at all). I have found a simpler workaround than the one discussed above.

All that is required is for the monitor to be powered off until the Mac starts loading the OS. I don’t pull any cable plugs and I only use the power button on the back of the monitor to power cycle it.

So from a cold start, I leave the monitor turned off until the startup chime from the Mac, and then turn the monitor on using the button. 

For a restart, I let the Mac shut down until the screen goes blank and then turn the monitor off at the button. As before, after the chime I turn the monitor on again.

I don’t think either of these sequences requires precise timing, but I guess the monitor needs to be off long enough for its USB bus to reset.

This workaround is not only simpler, it also avoids the wear and possible damage to plugs and cables subject to frequent disconnection, and on a restart it allows the MacOS to automatically unmount any attached devices.

My attached USB devices are all storage devices, so I allow this procedure may not work so well with other devices such as a USB keyboard (although a keyboard should work as USB2, so that is unlikely to be a problem). But there are many different USB devices. There are also many models of Mac hardware and MacOS versions.

Best would be for Dell to solve this problem - and soon. I am on the verge of returning my monitor because it fails to meet its advertised specifications.

(Posted also to Dell support group where the same discussion occurs.)

<< or if Apple engineers can weigh in from the macOS USB initialization side>>

Apple movers and shakers do not troll the Apple community discussions looking for problems. Apple engineers are prohibited from posting here.

if you want the attention of an Apple employees, you can post a terse description of the problem using the Product Feedback links:

Product Feedback - Apple

...or contact Apple support and work with them to get a resolution or a Formal, Tracked, Bug Report onto the reporting system. It will take working with a Specialist (not just a First responder) to get someone with enough depth.

Official Apple Support

My response was to check the specs on the interface on the display, to see if it was indeed sold as 2.5 Gig Ethernet capable. And yes indeed it was sold as 2.5 Gig Ethernet interface.

it is possible that the device can generate clocks and handle bursts of traffic, so as to participate on a 2.5 G Ethernet network. But not being able to provide sustained support at those transfer speeds is extremely deceptive.

Having the port always flow-controlled back to less than one-fifth the nominal speed (USB-2 of 480 M bits/sec rather than the assumed 2,500 M bits/sec) is not a full-featured interface. if there is no technical relief available, Selling it as a 'real' 2.5 G Ethernet interface is a deceptive business practice.

Grant Bennet-Alder wrote:

My response was to check the specs on the interface on the display, to see if it was indeed sold as 2.5 Gig Ethernet capable. And yes indeed it was sold as 2.5 Gig Ethernet interface.

The only downstream port on that monitor that looks like it has any business being on an internal USB 2.0 hub is the "Analog 2.0 audio line out port (3.5 mm jack)."

Dell – Dell UltraSharp 27 4K Thunderbolt Hub Monitor - U2725QE

I could not easily find specs on the chips used to create the Hubs used in the display.

What I wanted to see was whether those Hub chips were capable of higher than USB2 speeds, IF they were properly programmed. Or if that hardware was inherently not capable of higher speeds.