Can't use more than one port at a time on Apple USB-C Digital AV Multiport Adaptor

Apple quietly updates firmware for USB-C adapters through macOS.

Do this:

1. Connect the adapter to your MacBook Pro
2. Connect HDMI cable, USB-A device, and USB-C charger
3. Leave it connected for 3–5 minutes
4. macOS will update the adapter firmware in the background if applicable

Reboot afterward.

<< It has never allowed me to use more than one of its ports at a time. >>

That device is primarily an HDMI adapter.

you can also connect SIMPLE low speed USB devices to its USB-A port.

It's USB-C port is Charge-ONLY

The USB-C Digital AV Multiport Adapter lets you connect your USB-C—enabled Mac, iPad, or iPhone to an HDMI display, while also connecting a standard USB device and a USB-C charging cable.

¿What two allowed devices do you want to connect at the same time, that it fails to support?

the information I posted was pull-quoted from the sale page at the Apple online store:

The USB-C Digital AV Multiport Adapter lets you connect your USB-C—enabled Mac, iPad, or iPhone to an HDMI display, while also connecting a standard USB device and a USB-C charging cable.

As you can see, the USB-C port is intended only for charging, but it might have USB-2 connections, which will not be great for anything with a high data rate like an drive, unless you don't care how fast it runs.

You should be able to connect USB-A devices and have them work. iI not, the issue could be with the device, the cable, or the adapter. You would need to substitute know-good replacements until you can isolate the issue.

In November 2025 Apple released a firmware update for its “140W USB-C Power Adapter” — along with USB-C versions of its Magic Keyboard and Magic Trackpad — and those updates “install automatically when the accessory is actively paired to a device running iOS, iPadOS, macOS, tvOS, or visionOS.

https://www.macrumors.com/2025/11/18/apple-new-firmware-magic-keyboard-trackpad/?utm_source=chatgpt.com

The USB-C versions of Magic Keyboard / Magic Trackpad (i.e. the switch from Lightning to USB-C) were introduced in October 2024. MacRumors+1

The 2025 firmware update is the first firmware refresh since those USB-C versions shipped. MacRumors+1

That implies Apple hasn’t (publicly) done many — or any — firmware updates for these USB-C accessories between their 2024 launch and late 2025. One year without updates suggests the updates are infrequent. MacRumors+2Macworld+2

Older (non-USB-C) accessories — e.g. older Magic Keyboard/Trackpad — have received firmware updates as well, though not on a fixed schedule. For example, there was a firmware update for Magic Keyboard in January 2024 (version 2.0.6) addressing a Bluetooth security issue. 

So I am not sure how someone could possible suggest the Apple  USB-C Digital AV Multiport Adaptor has had a Firmware update

I do know, I purchased that same  USB-C Digital AV Multiport Adaptor back in about 2017 and it has yet to receive a Firmware update

You may ask OP to supply some Links to documents that would substantiate their suggestion

WildflowerSue wrote:

Thanks, I appreciate this information. I did try your suggestion - please see my responses to Grant and Owl-63.

Food luck getting a reply