Connect Two M1 Max MacBooks to LG 4k 24in Ultrafine

[lrb3000]

Hi!

I have two M1 Max laptops that I would like to connect to one LG 24MD4KL (24in 4k UltraFine). The LG monitor only has one input, so I will need some sort of switch that can accept two USB-C or Thunderbolt 3 input connections.

I found an AppleInsider article that says you can use this switch (CableDeconn USB-C Type-C 8K Switch). The problem is the Amazon listing says it is NOT compatible with MacBooks or LG Monitors (1st bullet under About This Item), but the AppleInsider article says it can be done. Note, I found it for sale other places and checked the manufacturer's website and that limitation wasn't noted anywhere else.

I do not need the monitor to display both laptops simultaneously. I just need to switch between the two laptops. Does anyone know if this will work or are there other suggestions on how to have the LG monitor switch it's input between two MacBooks (thunderbolt or USB-C)?

I appreciate any help! I have searched MacRumors forums for hours and haven't found a good answer.

 

[joevt]

The 24MD4KL has two Thunderbolt 3 ports - I think either one can be an input, but if you connect it to two Macs, only one can be used at a time. Maybe it will automatically switch between Macs when one goes to sleep? Or maybe one needs to be turned off completely for it to switch to the other Mac?

The switch could work. It may be able to do Thunderbolt at 20 Gbps which is sufficient for 4K60. With a Thunderbolt connection, the display's USB ports should be able to do 5 Gbps. If the displays connect as USB-C instead of Thunderbolt, then the USB ports will be limited to 480 Mb/s.

In any case, you don't want to switch while a storage device is connected to the display.

The article is incorrect about the Apple Pro Display XDR - it should work with the switch at 6K if the GPU and OS supports DSC.

 

[lrb3000]

The 24MD4KL has two Thunderbolt 3 ports - I think either one can be an input, but if you connect it to two Macs, only one can be used at a time. Maybe it will automatically switch between Macs when one goes to sleep? Or maybe one needs to be turned off completely for it to switch to the other Mac?

The switch could work. It may be able to do Thunderbolt at 20 Gbps which is sufficient for 4K60. With a Thunderbolt connection, the display's USB ports should be able to do 5 Gbps. If the displays connect as USB-C instead of Thunderbolt, then the USB ports will be limited to 480 Mb/s.

In any case, you don't want to switch while a storage device is connected to the display.

The article is incorrect about the Apple Pro Display XDR - it should work with the switch at 6K if the GPU and OS supports DSC.

Thank you so much for the input. I ordered the switch and it didn't work. I tried it with USB-C and Thunderbolt 3 cables. For some reason, it doesnt work with a MacBook attached to it (I tried Intel and M1 Macs). I also tried just connecting 1 MacBook to the switch and the switch to the LG monitor. The cables I tried all work when connected directly to the MacBook and monitor (to rule out cable issues).

Does anyone else have ideas on how to connect two MacBooks to the same monitor via a switch?

Thanks!

 

[joevt]

Thank you so much for the input. I ordered the switch and it didn't work. I tried it with USB-C and Thunderbolt 3 cables. For some reason, it doesnt work with a MacBook attached to it (I tried Intel and M1 Macs). I also tried just connecting 1 MacBook to the switch and the switch to the LG monitor. The cables I tried all work when connected directly to the MacBook and monitor (to rule out cable issues).

Does anyone else have ideas on how to connect two MacBooks to the same monitor via a switch?

Does the switch work with anything? A different computer? Different devices?

The Amazon page says Thunderbolt cables cannot be used - does a USB-C cable connected to an LG UltraFine 4K display count as a Thunderbolt cable since it can do 20 Gbps Thunderbolt? You can remove Thunderbolt from the Mac end by using a HP Thunderbolt Dock G2 which has a pure USB-C DisplayPort Alt Mode port.

The Amazon page says you cannot connect a USB dock - isn't a USB-C display basically a USB dock? Or do they mean you cannot connect a USB 3.x + DisplayPort dock but a USB
2.0 + DisplayPort USB-C dock is ok (which is what the LG UltraFine 4K is when not using Thunderbolt).

The Amazon page says you may need to use shorter cables. Does that mean you should replace all the cables with shorter ones?

There exists Thunderbolt 2 KVM which should work but I don't know if they are sold anymore
https://www.amazon.com/dp/B01M74Y03E

Maybe DisplayPort KVM is the way to go. Use Belkin Charge and Sync cable to connect USB 2.0 + DisplayPort to the LG UltraFine 4K displays.
https://www.kvm-switches-online.com/displayport-kvm.html
That website has many KVM options.
To turn USB-C to DisplayPort + USB 2.0, use a Cable Matters hub (ignore the Ethernet on this adapter since it is limited to USB 2.0 speed)
https://www.cablematters.com/pc-899...-usb-20-fast-ethernet-and-power-delivery.aspx
Or a Thunderbolt 3/4 dock hub.