Issue connecting 2020 MacBook Pro to external Dell SE2719HR Monitor

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mrh1988 Author

Level 1

8 points

Issue connecting 2020 MacBook Pro to external Dell SE2719HR Monitor

Hi,

I'm having an issue connecting my 2020 MacBook Pro to my external Dell SE2719HR monitor. It only recognizes a connection when I restart my computer with the monitor plugged in. If I unplug the computer from the monitor, or my computer falls asleep, the connection does not work upon replugging it in or waking my computer back up. I have another 2019 MacBook Pro that works perfectly fine with the monitor, so I'm wondering if it has to do with the OS on this particular computer.

Can anyone please provide some guidance as to what could be the issue and how to fix it?

Thanks!

Posted on Jul 26, 2020 8:48 PM

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Answer 1

Top-ranking reply

Axel Foley

Level 10

149,304 points

Jul 26, 2020 10:05 PM in response to mrh1988

How about trying out the following two troubleshooting methods to address your issue with the external monitor? Try the below methods ONE at a Time and see if either one resolves the issue.

Reset SMC by following the directions applicable to your MacBook here ➔ How to Reset SMC. If that does not solve things then-
Reset NVRAM/PRAM by following the directions applicable to your MacBook here ➔ How to Reset NVRAM/PRAM.

Which macOS is running on your 2020 and on your 2019 MacBook Pro? Are both on macOS Catalina or is the 2019 MacBook Pro running macOS Mojave? I am just curious.

Axel F.

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Answer 2

mrh1988 Author

Level 1

8 points

Jul 26, 2020 11:18 PM in response to Axel Foley

Hi Axel,

Thanks for the quick response. I tried both options and, unfortunately, I’m in the same boat as before. The monitor only connects when I restart the computer, but disconnects when it falls asleep. Both computers are updated on Catalina. I should mention that the computer I’m having issues with is my work one, so could it be the programs/settings set by my IT department? I’ll check with them, but if you have any other suggestions I’d appreciate it.

Thank You!

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Answer 3

Axel Foley

Level 10

149,304 points

Jul 27, 2020 12:32 PM in response to mrh1988

I agree that it is highly possible that the operation of the ports of your work MacBook are influenced by the IT group's profile. Let us know what you come with after the inquiry with IT. Thanks.

Axel F.

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Answer 4

mrh1988 Author

Level 1

8 points

Jul 27, 2020 5:24 PM in response to Axel Foley

Hey Axel,

I checked with my IT department and they actually recommended the same thing you did regarding SMC / NVRAM reset. Other than that there's really no other setting to change they said. Also, the laptop is brand new so there shouldn't be anything wrong with it. Weird. Maybe my best option is to keep my computer from falling asleep and disconnecting during the workday so I don't have to reboot every time. Please let me know if you can think of anything else. Thanks again for all the help.

Matt

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Answer 5

Jul 27, 2020 5:33 PM in response to mrh1988

to get a Mac display to become active, you need the Mac to query the display, and the display to answer with its name and capabilities. Otherwise, the display will not be shown as present, and no data will be sent to the display.

This query is only sent at certain times:

• at startup

• at wake from sleep

• at insertion of the Mac-end of the display-cable, provided everything on that cable is ready-to-go

• on invoking Option-(Detect Display) button in Displays preferences (from another display)

so try doing some of those things and see if the display comes alive.

Modern Displays with multiple ports are sometimes busy scanning the other ports, looking for an input, and miss the query from the Mac. They need to pay attention to the port you are actually using, or they will miss the query.

Some displays have On-Screen Display settings that can be used to tell the display a computer is attached on a certain port, or a certain port should be highest priority. Changing those may make your display more responsive.

Some displays include their own private "sleep" settings for the display alone. This can allow the display to enter its own sleep mode, on top of the Mac's not sending it data. A display that is sleeping on its own cannot respond to the Mac's query, and will stay dark.

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Answer 6

Axel Foley

Level 10

149,304 points

Jul 27, 2020 7:26 PM in response to Grant Bennet-Alder

Hi Grant,

What has us perplexed is that the OP's 2019 MacBook Pro, which is running macOS Catalina as well, is perfectly waking up the external display as it wakes from sleep. This MacBook Pro is OP's personal computer. The 2020 MacBook Pro, which is also running macOS Catalina, in not able to wake the external display from sleep and requires a recycle. This MacBook Pro is issue by OP's work.

Axel F.

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Answer 7

Jul 28, 2020 8:53 AM in response to Axel Foley

More divergent thoughts:

Can the display be seen reliably in Safe Mode? Safe Mode assumes default resolution fo the display, to get around the case where the resolution has been set too high. Changes made in Safe Mode will "stick" in regular mode.

If mirror displays is set, a compromise resolution is used, that is computed to support both displays, but sometimes one or the other display cannot use the computed resolution.

What adapters and cables are in use in each case? Computers have the ability to test the fastest reliable data rate, as a test for cable quality.

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Issue connecting 2020 MacBook Pro to external Dell SE2719HR Monitor

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