Thunderbolt monitor not detected

Question

Thunderbolt monitor not detected

I have a Macbook Pro 15-inch, 2017 and a Thunderbolt monitor. When I shutdown for the night, and reboot in the morning, the Thunderbolt monitor doesn't work (does not display). If I switch the Thunderbolt port connection, and reboot, sometimes that will work; other times, it will not.

What the heck is going on? Absolutely no operating system or otherwise MacOS changes are being made. How can a reboot just stop the Thunderbolt monitor from working?

Baffling. Any advice? Nothing seems to work. I've tried every reset in the book. I've reinstalled the OS numerous times.

MacBook Pro with Touch Bar

Posted on Apr 10, 2022 12:22 AM

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Answer 1

hcsitas

Level 6

13,970 points

Apr 10, 2022 1:13 PM in response to Shawn Chittle

Physically, their interfaces are different. To connect you need a 3-2 adapter like this one Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter - Apple. Is that what you’re using? Have you tried a new one?

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Answer 2

tbirdvet

Level 6

17,319 points

Apr 10, 2022 4:22 PM in response to Shawn Chittle

Go to preferences, energy saver and schedule the shut down nightly at the time you want and also auto start in the morning and see if the issue still exists.

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Answer 3

Apr 10, 2022 9:14 PM in response to tbirdvet

Although I can't conceive as to how a user-initiated shut down and startup differs from an automatic one, I will try it.

What's more likely is some kind of display bug in the OS that doesn't detect the monitor as well as it used to, and since they've stopped making this monitor long ago, its nowhere near the top of their bug list.

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Answer 4

hcsitas

Level 6

13,970 points

Apr 10, 2022 9:41 AM in response to Shawn Chittle

Have you tried a new dongle?

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Answer 5

Apr 10, 2022 1:01 PM in response to hcsitas

I’m unsure what you mean. All Thunderbolt 2 devices work on Thunderbolt 3. It’s backwards compatible.

My question is why does the MacBook stop working with the monitor on reboot? If I move the cable to another port, it works. Then I reboot and it doesn’t. Then I move the cable to another port and it works again.

Its madness. Please help!

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Answer 6

hcsitas

Level 6

13,970 points

Apr 10, 2022 3:16 AM in response to Shawn Chittle

What “Thunderbolt monitor”? If it’s non-Apple, try posting in the MacBook Community, this forum’s for Apple monitors only. Good luck!

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Answer 7

Apr 10, 2022 7:17 AM in response to hcsitas

Apple has made a Thunderbolt monitor for years.

It’s this one.

Apple Thunderbolt Display - Technical Specifications (TH)

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Answer 8

Apr 10, 2022 7:17 AM in response to tbirdvet

Manually.

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Answer 9

Apr 10, 2022 9:51 AM in response to hcsitas

The “dongle” in this case is physically attached to the monitor as a cable. It works most of the time. But not all of the time and that’s my question for the community. Is there a fix for this?

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Answer 10

hcsitas

Level 6

13,970 points

Apr 10, 2022 12:09 PM in response to Shawn Chittle

I meant on the MacBook side which has Thunderbolt 3 not 2.

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Answer 11

Apr 10, 2022 1:18 PM in response to hcsitas

That’s what I have. I suppose I could try another one.

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Answer 12

hcsitas

Level 6

13,970 points

Apr 10, 2022 1:19 PM in response to Shawn Chittle

Yup, I’d do that.

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Answer 13

tbirdvet

Level 6

17,319 points

Apr 10, 2022 4:36 AM in response to Shawn Chittle

When you state shut down at night are you manually shutting down or are you using the auto shut down and start up feature? I have the same setup but use the auto shut down and start up in the AM and no issues. I have not tested doing that manually.

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Thunderbolt monitor not detected

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