MacBook not recognizing external display

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Level 1

5 points

MacBook not recognizing external display

I have a MBP M1 Max to which I attach (thru USB-C cable) a Dell UltraSharp 27" monitor (U2720Q), using it as my main display. Every time I shutdown and log back in, the MB doesn't see it and I have to unplug the USB-C cable and re-attach the display and reset it as the main. I am using the USB-C port on the right side (facing the MB) as it is closest to the Dell.

This not only wastes time but also is an indication that either there is a hardware problem, or, I don't have things set up correctly. How do I resolve this problem?

Thanks.

Posted on Mar 30, 2023 08:31 AM

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Answer 1

Aug 23, 2023 08:01 AM in response to pebunn

This happened to me and it was so frustrating! All the forums and Apple support kept saying to get a new HDMI display cable for the monitor and restart my computer. I did that a hundred times, sometimes it works and sometimes it didn't - recently it hasn't for 2 weeks.

What worked was buying the USB-C connector cable adapter from Apple direct versus what I had been using for TWO years via Amazon. I even bought a new one of the same thing I had but it didn't work. It shows you how much apple is trying to require you to use Apple accessories?! https://www.apple.com/shop/product/MUF82AM/A/usb-c-digital-av-multiport-adapter?afid=p238%7CswgCviYzH-dc_mtid_1870765e38482_pcrid_616237453587_pgrid_142885899249_pntwk_g_pchan_online_pexid__&cid=aos-us-kwgo-pla-btb--slid---product-MUF82AM/A.

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Answer 2

Apr 18, 2023 11:29 AM in response to pebunn

that 4K display is a genuine Thunderbolt Display. To use all its features and downstream ports, it should be connected with an appropriately SHORT (0.8 meters or less) genuine Thunderbolt cable.

Interfaces

1 x DP 1.4 (HDCP 2.2)
2 x HDMI 2.0 (HDCP 2.2)
1 x Thunderbolt(TM) 3 Upstream port (DP1.4)

Otherwise, use an adapter to Its DisplayPort input.

HDMI is a step in the wrong direction, as HDMI is bandwidth-limited and requires a lot of "black magic' to get working correctly.

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Answer 3

pebunn Author

Level 1

5 points

Apr 18, 2023 11:11 AM in response to pebunn

Hello All,

I think that I found a workaround to this issue; consider the following:

1) When turning on the MB, I lift the lid just enough to reach in and hit the Touch ID (power button) and then quickly close it

2) Because the device only "sees" or senses the external monitor, it automatically designates it as the "Main" display, while keeping the Built-in Display as the "Extended" display.

I have tried this solution several times and it works - keeping the external display as the Main display - every time, and eliminates the need to unplug and re-plug the cable to the external display.

Thoughts?

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Answer 4

Aug 23, 2023 01:52 PM in response to phorton123

<< It shows you how much apple is trying to require you to use Apple accessories? >>

[in my opinion] you are mistaken. Apple provides some high-quality accessories as convenience for you. They do not provide all possible accessories. One glaring omission is that they do not offer USB-C to DisplayPort cables.

The issue is that recent versions of MacOS are now detecting transmission errors (when they did not before) on data are sent to the display, and either falling back to a lower resolution or disconnecting.

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