MacBook Pro M3 only recognizes one monitor

Thunderbolt TBT4-UD5
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Hey all, I just upgraded a user to a new MacBook Pro M3 and a new TBT4-UD5 dock, both from Amazon. I’ve got two monitors connected to the back of the dock via HDMI and the MacBook will not recognize more than one monitor at a time. It’s not a cable issue, since if I unplug one, the other will show, and vice versa. I read through a lot of documentation and it says this dock doesn’t need any drivers installed, is that correct? I’ve already tried powercycling and restarting the MacBook.

2

Hello gbgrizz,

Thank you for reaching out on the forums! I am sorry to hear that you are running into issues with your TBT4-UD5, but I would be happy to help diagnose the issue here.

Do you happen to have a base model M3 MacBook Pro? In other words, does your MacBook have the M3 Pro or M3 Max chipset, or is it just the “default” M3 MacBook Pro? If this is the case, then these MacBook’s only support a single external display when the lid is open, which means that the same limitations will be applied when connected to our TBT4-UD5.

Apple has recently released a macOS update that allows for 2x external displays when the lid is closed. You can see the display capabilities in the screenshot below or on the tech specs here:

996×165 8.28 KB

If you do have an M3 Pro or M3 Max MacBook Pro, please let me know!

Thank you,

Evan

Plugable Technologies

www.plugable.com/support

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Hi Evan, thanks for your response. I was able to verify it has a M3 Pro chip.

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Thanks for confirming that.

Next, can you confirm that you are using the included Thunderbolt 4 cable to connect the dock to the MacBook? The cable should have a cable tag on it indicating that it is for the TBT4-UD5. We’ve seen issues when third party cables are used.

Can you also confirm that this issue is present no matter which USB-C port you connect the dock to on your MacBook?

Thank you,

Evan

Plugable Technologies

www.plugable.com/support

5

Would the thunderbolt 4 cable that came with the dock have the Plugable logo on it?

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Evan, you were correct about the using the plugable thunderbolt 4 cable! I wasn’t the one who unboxed it so we were probably using just a usb-c cable, but I found the one that came with the dock and now the second monitor is showing. Thank you so much for your help!!

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Thanks for the response, and I am glad that I was able to help here!

Please do not hesitate to reach back out if you run into any other issues with your TBT4-UD5!

Thank you,

Evan

Plugable Technologies

www.plugable.com/support

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