My M4 Macbook Pro won't use the full resolution of my LG External Monitor

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AJBean16 Author

Level 1

4 points

My M4 Macbook Pro won't use the full resolution of my LG External Monitor

Macbook: Apple M4 Pro 24 GB, running Sequoia 15.6.1

Monitor: LG 27US500-W ULtrafine Monitor 4K UHD

Hub: Anker USB-C Hub, 10 in 1, with 4K@60Hz HDMI Display port

Cable: High Speed HDMI Cable with Ethernet, E508028-Z

Hi there, I'm hoping someone has some insight that can help me. I've got a new monitor for my Macbook because the old monitor was low resolution and needed updating. Now I have a 4K monitor, but my computer will still only let me use the 1920x1080 resolution when I plug it in. I'm using a docking station for all my accessories, but it is supposed to be capable of utilizing the 4K reolution. The HDMI cable came with the monitor, and is labeled as high speed with Ethernet. When I use my computer on a different monitor at home, it works just fine with the higher resolution monitor. But here at work, the system settings are capping me at 1920x1080. The monitor warns me when I turn it on that the computer is using too low of a resolution, but I can't figure out how to change it. When I click "Show all resolutions", this is what it gives me:

Any Suggestions on what I can do so that my monitor isn't all pixelated and grainy? Thank you so much for your help.

[Edited by Moderator]

MacBook Pro 14″, macOS 15.6

Posted on Sep 29, 2025 12:30 PM

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Answer 1

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AJBean16 Author

Level 1

4 points

Oct 7, 2025 10:39 AM in response to Servant of Cats

Thank you for pointing out that my Macbook Pro has an HDMI port! I was so used to my old MacBook that I honestly didn't even realize I had one now. I used that for troubleshooting, and that did the trick. I reached out to Anker for product support on the dock, they walked me through how to reboot the dock and install a driver for it, and now it's working perfectly. Thank you so much for this very simple, but so helpful troubleshooting tip.

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Answer 2

Sep 30, 2025 12:17 AM in response to AJBean16

Which particular Anker docking station do you have?

Model number, please.

In any case, your description of the thing as "USB-C Hub … 4K@60Hz HDMI Display port" makes me think that it's a plain USB-C hub that lets you hook up two or more displays at a time. That implies that it is using MST (which Macs do not support), or some sort of "workaround" (like DisplayLink), or both.

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Answer 3

Sep 30, 2025 12:29 AM in response to AJBean16

Since this is a 14" M4 MacBook Pro that has a built-in HDMI port, have you tried running a cable directly from the Mac's HDMI port to one of the monitor's HDMI ports, just as a test?

That might not be the most convenient long-term arrangement, but for short-term testing, it would cut out the hub from the equation … therefore possibly making troubleshooting easier.

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Answer 4

Sep 30, 2025 12:25 AM in response to AJBean16

LG – 27 Inch UltraFine™ 4K UHD HDR10 IPS Monitor 27US500-W

This is a 27", 3840x2160 pixel monitor with a refresh rate of 60 Hz and support for 10-bit-per-channel color.

It has one DisplayPort v1.4 input, and two HDMI v2.0 inputs.

HDMI v2.0 has bandwidth limitations such that you cannot have all of

3840x2160 pixel resolution
60 Hz refresh rate
10-bit-per-channel color
RGB 4:4:4 encoding

simultaneously. Something has to give. Usually the solution is to cut back to 8-bit-per-channel color, instead of reducing resolution, cutting the refresh rate to Hz, or using one of the lesser RGB encodings. (Those ones force two or more adjacent pixels to have the same color, and thus effectively cut resolution.)

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My M4 Macbook Pro won't use the full resolution of my LG External Monitor

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