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User profile for user: mydy
mydy Author
User level: Level 1
14 points

USB hub in external display doesn't work after OS restart

My problem is very similar to one described here: https://discussions.apple.com/thread/251168093


I've connected my new MBP M1 through USB-C to NEC EA271U. I'm using keyboard and mouse connected to USB-hub in monitor. Problem is that sometimes it doesn't work. I think that failing scenario is when I simply restart my MacBook. Then my external display shows the video output correctly, but USB devices doesn't work. To make them working I have to unplug and plugin the USB-C cable again. Then both video and USB devices are fine.


I think USB-C cable I'm using is OK as it's Belkin, supporting charing and 4k@60Hz.


I don't know how to troubleshoot this issue. Please advise what to do.


PS. Previously I was using this external monitor with my PC, but USB-hub was connected to PC using dedicated USB cable and video was transmitted by DisplayPort cable. So I'm not sure whether it's MBP fault or monitor issue.

Posted on Aug 17, 2021 12:23 PM

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11 replies
User profile for user: mydy
mydy Author
User level: Level 1
14 points

Aug 19, 2021 12:13 PM in response to a brody

Come on, stop trolling ;) I appreciate willingness to help, but I think you're trying to blame the cable while like I already said - it was working perfectly fine for months (on Windows/Intel machine). This cable is reliable.


Also, after turning the external display off/on, USB-hub works just fine so all that mean that MacBook is the problem here, not the cable or external display.

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User profile for user: mydy
mydy Author
User level: Level 1
14 points

Aug 20, 2021 6:56 AM in response to mydy

I've noticed that:


  • it doesn't matter which USB-C port I'm using (issue occurs on both 2 ports)
  • issue occurs not only after rebooting, but also after normal booting (I prefer sleep mode anyway than rebooting or shutting down and starting whole OS from scratch). In other words - if I want my external display fully working (with USB hub) I have to connect it AFTER I start my MacBook. Crazy.
  • when issue occurs, there is no USB hub info provided on This Mac -> System report -> USB.


I'm disappointed with my first MacBook Pro :/

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User profile for user: a brody
a brody
User level: Level 10
84,131 points

Aug 17, 2021 12:37 PM in response to mydy

If you have an underpowered hub, it won't work.


The specs you gave for the hub do not tell us if it takes on the full 100W as passthrough. If it doesn't then you need a better hub. USB-C cables come in different varieties too. There are some that carry more than just power. Make sure the one you use for the connection to the monitor does.

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User profile for user: mydy
mydy Author
User level: Level 1
14 points

Aug 17, 2021 1:16 PM in response to a brody

As the hub usually works correctly and it doesn't work always after restarting MacOS, I would say it's not underpowered.


PS.

This is spec of my monitor: EA271U_manual_EN_v5.pdf

And this is the cable I'm using: Belkin 1 m 3.1 USB-C Male to USB-C Male Cable (10 Gbps, 4k, 100 W/5 A PD, USB-IF Certified, Compatible with MacBook, MacBook Pro) https://www.amazon.co.uk/gp/product/B073KCPS2M

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User profile for user: a brody
a brody
User level: Level 10
84,131 points

Aug 17, 2021 1:21 PM in response to mydy

Straight from the Amazon link:


"Cable does not support Thunderbolt 3 USB-C to USB-C Cable supports Thunderbolt 3 and USB 2.0, however, does not support USB 3.0 and DisplayPort over USB-C"


Secondly, your monitor only supports USB-2 on the older USB connections. Thus there may be a lag down stepping to USB-2 from USB-3 devices.


The issue on power on may be your computer trying to resolve the oddities of lack of support.


Apple menu -> System Preferences -> Displays may need to "detect displays" to force the issue on some displays.

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User profile for user: mydy
mydy Author
User level: Level 1
14 points

Aug 17, 2021 1:37 PM in response to a brody

I don't get it, where did you find that part "Cable does not support Thunderbolt 3 USB-C to USB-C Cable supports Thunderbolt 3 and USB 2.0, however, does not support USB 3.0 and DisplayPort over USB-C" especially "Cable does not support" at the beginning? It looks like some odd copy&paste by accident.


What I see on Amazon page, there is a bullet point saying:

"Thunderbolt 3 USB-C to USB-C Cable supports Thunderbolt 3 and USB 2.0, however, does not support USB 3.0 and DisplayPort over USB-C"


Notice, there are two styles of this cable: Thunderbolt 3 and USB-C. Mine is USB-C. So my understanding is: that other type (which I don't have of course) aka "thunderbolt 3 USB-C to USB-C cable" supports Thunderbolt 3 and USB2.0...


I have USB-C style, which should support USB3.0 and DisplayPort over USB-C. BTW. I was using this cable with Dell Precision and docking station WD19TB for months, and I had no issues getting both 4k@60HZ and my USB mouse and keyboard working fine.










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USB hub in external display doesn't work after OS restart

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