Macbook Air M4 not supporting 2 external displays

Question

Level 1

4 points

Macbook Air M4 not supporting 2 external displays

I have Sequoia 15.6.1 installed. I have Samsung G9 and Samsung G5 2025. I am using 2 Ugreen high-end Display Port to USB-C type cables.

When I plug G5 first and then G9 next, G9 goes into a Screen Mirroring mode.

When I plug G9 first and G5 next, G5 doesn't detect the Display Port connection and stays blank.

Before purchasing Macbook Air M4, I have checked in numerous sources that it supports 2 external displays. What am I doing wrong here?

I tried Pluggable hub for my second external monitor with HDMI also but does not detect.

Please advise.

Thank you.

MacBook Air 13″, macOS 15.6

Posted on Aug 29, 2025 11:12 PM

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Answer 1

Aug 30, 2025 07:38 AM in response to sp85dav

Your Mac supports two displays in the following configuration:

Two displays up to a native resolution of 6K (6144 x 3456) at 60Hz or 4K (3840 x 2160) at 144Hz

The G9 is 5K wide with a 240 Hz refresh. I suspect that’s the issue. Try connecting the G9, selecting a lower refresh rate in System Settings > Displays, then connecting the G5.

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Answer 2

Aug 30, 2025 10:15 AM in response to sp85dav

The issue may have to do with the fact that the G9 is an ultrawide display. Sometimes ultra wide displays can have odd issues on Macs.

One other thing not all "high end" cables are created equal. If it is a DisplayPort cable, if it is not VESA certified there is no guarantee that it meets all DisplayPort specs. The same is true with HDMI cables. If they are not HDMI certified, there is no guarantee that the cable fully meets HDMI specs. Certified cable will have a clear marking on the cable of the DisplayPort logo or the HDMI logo if it is certified.

I suggest getting certified cables and make sure they are no longer than 1 meter in length.

Just to be clear, are both cables plugged into a hub or just one? If both are plugged into the hub are you sure the hub a sufficient bandwidth to support both displays or even one?

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Answer 3

sp85dav Author

Level 1

4 points

Aug 30, 2025 07:56 AM in response to neuroanatomist

I already have tried putting G9 on 60hz, lowered resolution (just in case) and didn’t work. Unable to detect G5.

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