USB-C (3.1 Gen 1) E...
 

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[Closed] USB-C (3.1 Gen 1) External Display

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I know its a stereotype that half the population here work in IT, but I could really use a bit of technical advice. This is probably really simple, but I’m currently stumped.
I am waiting for a new Macbook (stuck in Shanghai at present) and have shelled out some more money on a USB-C monitor (Benq) and Thunderbolt 4 hub Kensington 5700t) to connect peripheral SSDs/ethernet etc via a singe TB4 cable to the MacBook.
I have been trying to get my work laptop, a Lenovo ThinkPad E15, to work in the same way.
I can connect it to the monitor directly with the standard USB-C cable included in the monitor, and the TB4 cable which came with the dock. I cannot however get it to connect to the monitor through the dock.
It recognises the monitor as a USB device, but doesn't generate any image on screen. Instead I get a windows notification that “Display May Be Limited”. I’ve borrowed another TB4 cable this evening to run between the monitor and the hub but this has made no difference.

From Lenovo’s website the USBC port on the laptop is 3.1 Gen 1 and supports Displayport, so it ‘should’ work, but somehow going through the hub seems to mess it up. The fact is does work when connected directly suggests the hub is somehow the cause of the problem. All of the peripherals show up fine so the USB connection between the hub and laptop is working fine.

What am I doing wrong? And, slightly more importantly is the hub going to play up with the MacBook when it arrives?

Sorry for the ramble, but having updated drivers etc I’m no further forward.

Thanks,

Dicky


 
Posted : 01/12/2021 10:09 pm
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I have a Benq monitor and a Aimos 4 ports USB switch. I connect 3 different computers by USB to the switch to all be able to use the same keyboard/mouse/microphone/camera but for the display they have to connect direct to the screen. I couldn't get the screen to work through the switch.

Possibly not the same thing as you and probably of no help but make of it what you will.


 
Posted : 01/12/2021 10:17 pm
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i'd have a guess it's just a limitation of the machine tbh. Probably just doesn't expect a monitor to be connected through the hub via usb, though I'm just guessing.

I've got an m1 air and I connect my 27in 4k Lg through a usb-c hub, but the hub does have an hdmi port on it. Not sure if it would be recognised through the usb ports or not, never tried to connect that way, but the macbook does connect through the hub.

tbh, I'd say best just to google the configuration you are doing, surely someone has done it before.


 
Posted : 01/12/2021 10:27 pm
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From the website:

https://www.kensington.com/p/products/device-docking-connectivity-products/laptop-docks-usb-accessories/sd5700t-thunderbolt-4-dual-4k-docking-station-with-90w-pd/

Compatibility
Universally *compatible, this Thunderbolt™ 4 desktop docking station is the first of its kind, providing the ultimate plug-and-play solution for Thunderbolt™ 4 Window 10 laptops and Thunderbolt™ 3 MacBooks running macOS 11 (Big Sur) or later, while also supporting Thunderbolt™ 3, Thunderbolt™ 4, USB-C and USB4 accessories. For Thunderbolt™ 3 based Windows 10 laptops, please see our range of Thunderbolt™ 3 docks. *For Thunderbolt 4 enabled Surface devices, please see SD5750T

It's not compatible with Windows Thunderbolt 3 devices.


 
Posted : 01/12/2021 10:35 pm
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I think the issue is probably that the monitor works fine in in DP mode over USB because it’s not trying to split limited bandwidth between the monitor and the USB functions of the hub.

It appears that some hubs are smart enough to throttle the USB to USB 2.0 speeds to give the screen the majority of the bandwidth and it all works. I’m guessing your hub isn’t one of those.

https://dancharblog.wordpress.com/2021/01/03/4k60-monitor-plus-usb-devices-from-single-usb-c-laptop-port/

P.S. your laptop only has one port with the max bandwidth. You’re using that one, yeah?


 
Posted : 02/12/2021 6:56 am

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