Should a USB Switch work with late 2018 MacBook Air

Question

I have a UGREEN USB 3.0 Switch. It has 4 USB A sockets on one side and 2 on the other. Its point is to share the 4 things plugged in on one side with 2 computers. I've been using it with a 2014 MacBook Pro and a 2017 Razer Blade sharing a keyboard, mouse, and USB ethernet adaptor for the last 3 months.

Today I got a late 2018 MacBook Air. I tried connecting it to the same switch but it's not working and so I'm wondering where the issue is. It could be

1. Bad cables. I'm using USB C to USB A cables. I've used these cables for other things in the past. I tried 2 3 different cables. An Anker Cable, a TacMad cable, and a Elecom USB3-AC15 USB 3.1 cable. All 3 cables work fine for other USB devices

2. Wrong cables? Maybe there is more than one kind of USB-C to USB-A cable?

3. Bad Switch. The switch works but maybe something is incompatible?

4. This isn't supposed to work. I have no idea but maybe there is something about USB-C that makes it just not suppose to work

5. ???

To add to that I have a VANMASS 9-in-1 USB HUB. If I plug that between the switch and the macbook air everything works. In other words

[2014 MBP]<---------USB-A-USB-A-cable--------->[USB Switch]<->[Mouse] works

[2018 MBA]<---------USB-C-USB-A-cable--------->[USB Switch]<->[Mouse] doesn't work

[2018 MBA]<->[USB Hub]<---USB-A-USB-A-cable--->[USB Switch]<->[Mouse] works

Note that this is both without and with external power to the switch. Without power the switch doesn't light up (it does with the MacBook Pro and Razer). With power it does light up and pressing the button on the switch switches the LED indicator on top of the switch but the MacBook Air still doesn't see the mouse and keyboard without the hub in between

I'd like to not need the hub. It seems like I should be able to connect the MacBook Air directly to the switch just like I was doing with the MacBook Pro

Any idea what the issue is?

Answer 1

In my investigations, I have found that for a switch to work successfully, it needs to be connected to a USB hub. Even the Apple USB/HDMI to USB-C adapter will do.

Also, plugging a USB switch after the KVM switch helps to deal with some devices (My USB mic) that seem to cause trouble when directly plugged into the KVM switch.

The two switches I have experimented with are the USB3.0 4 port 2 way KVM from UGreen and a similar one from Belkin. (No HDMI, only USB switching)

It is a little finicky, and I am not sure why. The same switch works flawlessly between by Thinkpad and Desktop (Windows)

Hope this helps.

This is what my ioreg -p IOUSB currently looks like:

+-o Root  <class IORegistryEntry, id 0x100000100, retain 23>
  +-o AppleUSBXHCI Root Hub Simulation@00000000  <class AppleUSBRootHubDevice, id 0x100000405, registered, matched, active, busy 0 (0 ms), retain 13>
  | +-o USB 10/100/1000 LAN@00200000  <class AppleUSBDevice, id 0x100000407, registered, matched, active, busy 0 (0 ms), retain 14>
  | +-o USB3.1 Hub@00100000  <class AppleUSBDevice, id 0x1000019d1, registered, matched, active, busy 0 (0 ms), retain 12>
  +-o AppleUSBXHCI Root Hub Simulation@01000000  <class AppleUSBRootHubDevice, id 0x100000418, registered, matched, active, busy 0 (0 ms), retain 8>
  +-o AppleUSBVHCIBCE Root Hub Simulation@80000000  <class AppleUSBRootHubDevice, id 0x100000433, registered, matched, active, busy 0 (0 ms), retain 15>
  | +-o FaceTime HD Camera (Built-in)@80200000  <class AppleUSBDevice, id 0x100000435, registered, matched, active, busy 0 (0 ms), retain 14>
  | +-o Apple T2 Controller@80100000  <class AppleUSBDevice, id 0x100000439, registered, matched, active, busy 0 (0 ms), retain 13>
  | +-o Apple Internal Keyboard / Trackpad@80500000  <class AppleUSBDevice, id 0x100000440, registered, matched, active, busy 0 (1 ms), retain 20>
  | +-o Headset@80400000  <class AppleUSBDevice, id 0x100000446, registered, matched, active, busy 0 (0 ms), retain 11>
  | +-o Touch Bar Display@80600000  <class AppleUSBDevice, id 0x10000044a, registered, matched, active, busy 0 (0 ms), retain 13>
  | +-o Ambient Light Sensor@80300000  <class AppleUSBDevice, id 0x10000044e, registered, matched, active, busy 0 (0 ms), retain 11>
  | +-o Touch Bar Backlight@80700000  <class AppleUSBDevice, id 0x100000456, registered, matched, active, busy 0 (0 ms), retain 11>
  +-o AppleUSBXHCI Root Hub Simulation@14000000  <class AppleUSBRootHubDevice, id 0x10000046a, registered, matched, active, busy 0 (0 ms), retain 9>
    +-o USB2.0 Hub@14100000  <class AppleUSBDevice, id 0x1000019be, registered, matched, active, busy 0 (0 ms), retain 14>
      +-o USB-C Digital AV Multiport Adapter@14120000  <class AppleUSBDevice, id 0x1000019e2, registered, matched, active, busy 0 (3 ms), retain 12>
      +-o USB2.0 Hub@14110000  <class AppleUSBDevice, id 0x100002349, registered, matched, active, busy 0 (1 ms), retain 14>
        +-o IOUSBHostDevice@14114000  <class AppleUSBDevice, id 0x100002364, registered, matched, active, busy 0 (1 ms), retain 14>
        | +-o HHKB Professional@14114100  <class AppleUSBDevice, id 0x100002378, registered, matched, active, busy 0 (3 ms), retain 12>
        | +-o USB Receiver@14114300  <class AppleUSBDevice, id 0x10000238b, registered, matched, active, busy 0 (6 ms), retain 16>
        +-o USB2.0 Hub@14111000  <class AppleUSBDevice, id 0x1000023ed, registered, matched, active, busy 0 (1 ms), retain 15>
          +-o Samson GoMic@14111100  <class AppleUSBDevice, id 0x100002405, registered, matched, active, busy 0 (11 ms), retain 18>
          +-o HD Pro Webcam C920@14111200  <class AppleUSBDevice, id 0x100002454, registered, matched, active, busy 0 (13 ms), retain 19>
          +-o Flash Drive@14111300  <class AppleUSBDevice, id 0x100002f5a, registered, matched, active, busy 0 (4 ms), retain 12>

The USB-C Digital AV Multiport (at address 0x1000019e2) was necessary for the switch to function. But it was still being finicky with my USB mic (Samson GoMic@14111100) so I added a USB2.0 Hub@14110000 (this one by Sabernet) in-line and everything is working well.

Answer 2

The link to the USB switch is dead. Even so I think I found all I need to know about it from this.

It has 4 USB A sockets on one side and 2 on the other.

No wonder it doesn't work, it's using USB-A ports as inputs.

The USB-A port is not to be used as an input, doing so can damage USB hardware that complies with the USB specification. The switch, and any cables that came with it, are non-compliant with the USB spec and continued use is running the risk of damaging something far more valuable than the USB switch. I know you don't want to hear this but that USB switch is junk, throw it away. It will not work with any USB compliant cables you will find. Looking for non-compliant cables to work with this switch means buying cables that can damage anything that complies with the spec. I'll take this point by point.

Bad cables.

Your new cables sound fine, the cables that came with the switch are "bad", they were built in a way that violates the USB spec. They had to in order to use USB-A as an input on the switch.

Wrong cables? Maybe there is more than one kind of USB-C to USB-A cable?

There is more than one kind of USB-C to USB-A cable. The kind you want have the USB trident icon on them. It's not illegal to make a cable that does not comply withe the USB spec. It is illegal to not comply with the spec and use the trademark on the cable without permission.

There is no "right" cable for this switch because a compliant cable will not work and the cable that will work is non-compliant. Once this switch is gone then that means looking for the right cables for what replaces it, and that's not known until you find a replacement.

Bad Switch. The switch works but maybe something is incompatible?

The switch is incompatible with the USB spec. That makes it "bad" in my mind.

This isn't supposed to work.

It's not likely to work, whether it is supposed to or not.

???

Indeed. It's a big question on how this got passed any QC checks. Get rid of the USB switch and all cables it came with, they do not comply with the USB spec and can damage hardware that does comply.

If you are using this USB switch to share a keyboard, mouse, and ethernet then it sounds like you need a KVM switch, not a USB switch. KVM means "keyboard, video, mouse" and are common for when people want to use two computers on one desk. If you are switching USB and video separately then a KVM switch will save on that. If you must share the Ethernet adapter then look for a KVM switch with USB accessory ports. I'd find a way to not share that Ethernet adapter if possible, that just sounds like trouble.

Answer 3

I actually got this to work with my MacBook Pro 2021. According to UGreen's website here: https://www.ugreen.com/products/ugreen-usb-3-0-4-port-switch, it states:

How to Use It on USB C Port of Your Laptop

Since the USB C to A data cable basically doesn't support the OTG function, if you want to use this product on a USB C port, please use an OTG USB C to A Adapter with our USB A to A cable.

So, to make it work, you use a USB C to A adapter.

[2021 MBP]<--->USB-C-USB-A-Adapter<--->USB-A-USB-A-cable<--->[USB Switch]<->[Mouse] works

My Pixel phone came with a USB C to A adapter, so I tried that out, and it works now.