MacBook Pro not recognizing ethernet or audio output from USB hub monitor

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MacBook Pro not recognizing ethernet or audio output from USB hub monitor

I recently purchased a USB hub monitor (a Dell UltraSharp 27 4K USB-C Hub Monitor - U2723QE). I have my MacBook closed and connected to the external display via USB-C. The monitor has been working well with two exceptions: I'm not able to use the ethernet port or audio output on the monitor.

I'm able to see the monitor in the list of audio output sources in the "Sound" preferences pane. However, if I select the monitor, the volume control becomes grey and I can't adjust it. There is no sound from the 3.5 mm jack on the monitor.

For the ethernet connection, the situation is more complicated. The ethernet initially worked flawlessly when I first connected the MacBook to the monitor via USB-C. There was some kind of pop-up box that I don't remember that said something like "Do you want to use this ethernet connection?", to which I said yes. However, I subsequently disconnected the ethernet cable from the monitor and the MacBook has never been able to use the ethernet connection again after I plugged it back in. I have tried deleting the "USB 10/100/1000 LAN" service from the "Network" preferences pane many, many, many times, but the MacBook continues to say this service is "Not connected" with no further information.

Of the two issues, the ethernet connectivity is more important. I can use the audio port on the MacBook as a less desirable backup option if necessary. However, the ethernet connection is a must (and also clearly possible since it worked previously). Any debugging assistance is welcome. Thanks very much!

Posted on Dec 29, 2024 2:48 PM

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Answer 1

Top-ranking reply

parameter_poem Author

Level 2

285 points

Jan 2, 2025 12:25 PM in response to Grant Bennet-Alder

Sure. Here's what ended up working. Not sure if all of this is important or necessary.

0) I let the monitor sit unpowered and unconnected for several hours, as recommended in this thread.

1) I tested the Ethernet cable going into the monitor by connecting it directly to a different computer (i.e., not the MacBook that was having trouble with the monitor). That confirmed that the Ethernet connection was functioning properly. Not sure if this is important, but I used a PC laptop that had an Ethernet port directly on the device, so there was no need for dongles (this is also the only other computer I had available for testing).

2) Immediately after testing on the other computer, I reconnected the active Ethernet cable to the monitor while the monitor was connected to the MacBook via USB and both the monitor and the MacBook were turned on. For whatever reason, this prompted the monitor to start recognizing the Ethernet connection again and forwarding it to the MacBook via USB-C.

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Answer 2

Dec 29, 2024 2:53 PM in response to parameter_poem

these modern high-end displays have more complex computers in them, and when they mess up, the solution is not obvious. I recommend you give that display a Time-out. Disconnect all data and power and let it sit by itself for a quarter hour. (Facing it into the corner or making it sit on the naughty-stair is optional.)

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Answer 3

Dec 31, 2024 1:50 PM in response to parameter_poem

another line of attack is to se what your Mac thinks is connected.

Settings > General > (System Report) center at bottom ...

then Hardware > USB...

and look at what is hanging off the Display Hub.

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Answer 4

Dec 31, 2024 1:25 PM in response to parameter_poem

settings > network

is the interface shown in the list? if not, use the add [+] button below the list of interfaces to Add it to the list.

is the interface TOPMOST? If not, use the gear or [...] Icon to choose Set Service Order and drag Ethernet TOPMOST. It can stay there -- if no cable is connected, the next WORKING interface will be selected instead.

if the interface is shown, what is its status?

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Answer 5

Dec 31, 2024 11:49 AM in response to Grant Bennet-Alder

I also tested the ethernet cable connected to the monitor by disconnecting it from the monitor and connecting it to a PC. The connection worked immediately and provided about 80 Mbps. So, the problem appears to be specific to the MacBook.

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Answer 6

Jan 2, 2025 12:13 PM in response to Grant Bennet-Alder

After a call to the customer support line for the monitor, I confirmed that the problem was with the monitor, not the MacBook. So, problem solved, fortunately. Thanks to Grant Bennet-Alder for the helpful suggestions.

In case it's helpful at all, the active connection is the USB 10/100/1000 LAN, and it is shown in green at the top of the list of network options in the preferences pane. Previously, this USB LAN option appeared as red.

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Answer 7

Dec 31, 2024 11:45 AM in response to Grant Bennet-Alder

Thanks very much for the suggestion. I turned off the monitor and disconnected all cables for about 12 hours. I reconnected everything this morning and tried again.

The good news: the headphone jack now works fine for audio output. For some reason, there is no system-wide volume control, so I have to manage volume from individual apps (i.e., with the volume control next to videos, for example). But, this is definitely an improvement.

The bad news: no change in the internet situation. The MacBook still makes no attempt to connect to the internet via the ethernet connection on the display.

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Answer 8

Jan 2, 2025 12:17 PM in response to parameter_poem

Your posting will be here for a long time, and others may find it by searching.

it would really help "the best guy" if you could post a summary of what it took to get this going for you.

Thanks so much!

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MacBook Pro not recognizing ethernet or audio output from USB hub monitor

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