Docking station MacBook Air M3

I just looked in the online manual for the Asus dock. It says that the dock has

• 2 x HDMI 2.1 ports
• 1 Thunderbolt 4 port (DP 1.4, 3840*2160, 60 Hz / 40 Gbps / 5V – 3A)

Under Display Resolution, there is a note

"** As some notebook models do not support MST function or have limited bandwidth for display, please check with the device manufacturer for more details."

You might want to ask Asus if it matters WHICH ports you use. Just speculation – but maybe the dock drives the two HDMI ports using some MST arrangement that Macs don't support. Maybe if you plugged one monitor into one of the HDMI ports, and a USB-C (DP) to HDMI adapter cable into the Thunderbolt daisy-chaining port, things would work.

Just a stab in the dark, but it wouldn't hurt to check.

Thunderbolt docks that support three displays are a fairly recent arrival on the scene. While I'm pretty sure that they are designed to use a computer's native hardware video support, I'm not sure exactly how this meshes with how Macs have traditionally supported Thunderbolt 3 docks. (I.e., one 5K/6K display, or up to two 4K ones.)

Educated guess: The Asus dock and the Mac are both working properly, as designed. Each design has its own limitations, and these limitations work together to produce the behavior that you are seeing. The Mac is more at fault than the Asus dock, but neither is defective.

• The Mac is sending two streams of DisplayPort data over the Thunderbolt cable to the Asus dock.
• The Asus dock is not dynamically redirecting these streams based on what displays are plugged in. It is using Stream 1 to drive its HDMI ports, and Stream 2 to provide a video signal on its Thunderbolt daisy-chaining port.
• The Asus dock is using the internal equivalent of DisplayPort MST daisy-chaining to attach two internal DP-to-HDMI adapters to Stream 1.
• That might work if it was attached to a Windows PC that supported DisplayPort MST daisy-chaining. Since the Mac doesn't, if you plug your two monitors into the dock's two HDMI ports, they always mirror each other. This is because the Mac is only willing to provide one video signal on Stream 1, and the dock is not clever enough to grab Stream 2 away from the Thunderbolt daisy-chaining port and use it for the second HDMI port instead.
• The Mac might not even be aware that the second HDMI-attached monitor is present and is receiving a copy of the video being sent to the first one. That would explain why System Settings > Displays only showed a picture of one external display.
• Using a HDMI port and the Thunderbolt daisy-chaining port works because in that arrangement, you're using a different Thunderbolt-encapsulated DisplayPort video stream for each monitor.

Wishmaster40 wrote:

Thank you for your reply.

The first docking station doesn't anything but charge so I will speak to Ugreen about it.

To get it to display different images on different monitors, I think you would need to install DisplayLink software. I don't see an online manual – but I expect that the printed manual will tell you to go to the Synaptics site. (That is what the instructions for DisplayLink-based products from other vendors often tell you to do.)

Synaptics - DisplayLink

DisplayLink KnowledgeBase – Troubleshooting: macOS

Note that while this would might let you use two external displays with the lid open, it could also come with some significant compromises, as you would be bypassing native hardware support in favor of a workaround.

The second Asus docking station doesn't work with the lid open but with the lid it clones both screens on the monitor so basically I just have 1 screen twice. Any idee why this is the case?

That one appears to be a genuine Thunderbolt dock. When your M3 MacBook Air's lid is closed, it should be able to drive two displays via this dock. (Hopefully it will let you plug both into the dock full-time, instead of expecting you to plug the second one into the dock only after the lid is closed.)

I would second varjak.paw's suggestion of checking that your Mac is set up to use extended desktop mode.

Extend or mirror your Mac desktop across multiple displays - Apple Support

It is a brand new M3 MacBook Air which should support 2 screens, right?

MacBook Air (13-inch, M3, 2024) - Tech Specs - Apple Support

MacBook Air (15-inch, M3, 2024) - Tech Specs - Apple Support

Use dual monitors with your MacBook Air and MacBook Pro with M3 chip - Apple Support

----------

Simultaneously supports full native resolution on the built-in display at 1 billion colors and:

• One external display with up to 6K resolution at 60Hz
• Close the MacBook Air lid to use a second external display with up to 5K resolution at 60Hz

----------

If you wanted to drive two external monitors with the lid open, you would need a MacBook Pro with a Pro chip or a Max chip.

Wishmaster40 wrote:

1. Thank you for the detailed explanation!!

So basically there is nothing I can about it and just use the convert or buy a HDMI thunderbolt cable.

If plugging a USB-C to HDMI adapter (or adapter cable) into the Thunderbolt daisy-chaining port on the dock works, just keep doing that.

If I would get a MBP M4 MAX will I have the same issue with the ASUS docking station?

I think so.

Maybe Apple will have a change of heart, and decide to support DisplayPort MST on future Macs – but I wouldn't bet on it. Lack of DisplayPort MST support is a long-time issue with Macs, going back many years – and the way Mac users deal with it is to plug displays into different Mac host ports, or to use Thunderbolt docks to attach two monitors.

It might be interesting to see what happens once Apple and others start implementing Thunderbolt 5.

Intel Newsroom - Intel Introduces Thunderbolt 5 Standard

varjak paw wrote:

As to the second dock, the M2 and M3 MacBook Air will support only two monitors, not three

The M2 MacBook Air only supports one external display, period. It doesn't matter whether the lid is open or shut.

The M3 MacBook Air only. supports one external display when the lid is open. If you close the lid, it can redirect the hardware resources that would have supported the built-in screen to support a second external display. But you must close the lid – as noted in the Technical Specifications and in this Support article.

Use dual monitors with your MacBook Air and MacBook Pro with M3 chip - Apple Support

You can only drive two monitors from the same dock in a first-class, hardware-supported way if

• The Mac in question supports multiple external displays, and
• That dock is a Thunderbolt dock

None of the UGREEN Revodok hubs or docks appear to be Thunderbolt devices, with the exception of the UGREEN Revodok Max 213 Thunderbolt 13-in-1 Docking Station, which lists for $333 USD.

The UGREEN Revodok Pro 209 9-in-1 4k HDMI Universal Docking Station, which lists for $199, is expensive enough to be a Thunderbolt dock, but it isn't one. Based on UGREEN's description, you can use it to drive two monitors, in extended desktop mode – but only in a second-class way, using DisplayLink workaround technology. You'd need to install DisplayLink software on your Mac, and then the video for some or all of your monitors would be handled in a second-class way using software methods, rather than your MacBook Air's native hardware video support.

As to the second dock, the M2 and M3 MacBook Air will support only two monitors, not three, and to my knowledge a dock won't change that. So with the screen open, it's not going to give you two separate displays on the two external monitors. As to the two being duplicates when the screen is closed, check the Display settings and see if it's set to mirror the primary display.

For the UGreen dock, I'd suggest talking to their support resources.

As to what any future MacBook Air might support and what would work best with it, none of us here will have any idea.

Regards.

I offered a suggestion to your issue with the Asus when I replied before. Did you check that possibility?

The first link you posted in your most recent post doesn't go to a specific product, so we're not sure what you're considering. So we can't tell whether it will work with your current MBA nor with an M4 MacBook Pro.

Regards.

Wishmaster40 wrote:

However when I close the lid both monitors are duplicated and I can only add 1 more monitor which is my iPad Pro.

The iPad Pro is using a software connection method that doesn't count against your MacBook Air's hardware-supported display limit. It's just that the software for this (Sidecar) happens to be built into macOS & iPadOS, rather than being a third-party add-on.

Why does the docking doesn't see the second screen?

Also I tried removing both HDMI cables and add them 1 by 1 but the result is the same.

One guess is related to the fact that your Mac only supports a second screen at some times, and not at others. Maybe you need to plug the second display into the Thunderbolt dock after the lid of your MacBook Air is shut, and things are up and running with the first display. But you said that you tried that, and it didn't help …

Monitors are supposed to have unique IDs, but sometimes a manufacturer will cheat and give the same ID to a number of monitors. If you are unlucky enough to get two from the same batch that have the same ID, that can cause issues. Unfortunately, System Information (Option- / System Information…) does not appear to display this information. (If it did, I would suggest plugging in the monitors one at a time, writing down the IDs, and then comparing them, to see if they differ.)

As I said I would like a docking that works for my MBA and 1 that works for my MBP M4 Max when it is released. Or the Asus docking station will work for both?

If the M3 MacBook Air will let you plug in a Thunderbolt dock that already has two monitors connected, then any Thunderbolt dock (with suitable provisions for dual displays) should work both on the M3 MacBook Air and on a future, hypothetical M4 Max MacBook Pro.

Since we are not down to the case where you are using a Thunderbolt dock with a M3 MacBook Air whose lid is closed, you may want to contact Asus technical support and/or Apple technical support.

Because my other 2 monitors are HDMI output only I wonder which other docking I should purchase if we can get the Asus to work without additional software.

UGREEN Revodok Max 213 Thunderbolt 4 Dock 40Gbps

CalDigit Thunderbolt 4 Pro-dock

UGREEN would not be my first choice for a Thunderbolt dock, mainly because I'm not familiar with them as being one of the main long-term vendors in that area. My impression is that OWC, SonnetTech, and CalDigit have been catering to Mac Thunderbolt users for years, and would be likely to have a deeper bench of experience/expertise when it came to technical support.

That said, it's possible that the issues that you are encountering have nothing to do with problems with the Asus dock. E.g., if your two monitors are incorrectly set up to report the same electronic serial number, that's not the fault of the Asus dock – and would be likely to cause the same problems with any other dock.

Wishmaster40 wrote:

Especially for my new MBP M4 MAX I want a proper docking station that work, which docking station would you recommend?

How about the Asus Thunderbolt dock that you already have?

I don't see the need to use a USB-C (DP) to HDMI adapter to be a pressing reason to discard it, or any other, Thunderbolt dock, out of hand.