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USB problem/Thunderbolt on Mac mini M4

(USB mouse & keyboard) intermittent connection problems through various adaptors & cords:


Connected to the Apple USB-C to USB Adapter through the front USB-C ports - ok there.


But, on the back Thunderbolt ports, using my OWC Thunderbolt-to-USB-C adapter cord connected with a USB-C female-to-USB-A female adapter with either the mouse or keyboard does not hold a strong connection, sometimes not at all.


3 back ports and they're relatively useless to me right now. Any suggestions to make this Thunderbolt work?

Mac mini, macOS 15.1

Posted on Nov 23, 2024 2:46 PM

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Posted on Nov 23, 2024 5:22 PM

Lose the extra cabling and adapters at the mouse and keyboard port. The USB keyboard and mouse don't require anything but a simple USB-A to USB-C adapter to connect to the ports on the back of the Mac mini. They are simple and affordable @ about $10 a pair on Amazon.

They look like this:


In fact, if your keyboard has USB pass-through you only need a single connection to the Mac mini. You can daisy chain your mouse through the keyboard. Unless I'm misunderstanding something here.

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Nov 23, 2024 5:22 PM in response to swipod touch

Lose the extra cabling and adapters at the mouse and keyboard port. The USB keyboard and mouse don't require anything but a simple USB-A to USB-C adapter to connect to the ports on the back of the Mac mini. They are simple and affordable @ about $10 a pair on Amazon.

They look like this:


In fact, if your keyboard has USB pass-through you only need a single connection to the Mac mini. You can daisy chain your mouse through the keyboard. Unless I'm misunderstanding something here.

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Jan 15, 2025 9:34 AM in response to swipod touch

I’ve having the very same problem with my newly purchased base-model M4 Mac Mini. My old Apple Extended Wired USB Keyboard simply won’t be recognized, or intermittently stops working (same with my old LogiTech USB wired mouse).

i’ve tried plugging them in independently, and switching out the third-party adapter to an Apple made more than the results are exactly the same. Never, ever had any issues with this keyboard and mouse with any other Mac I’ve owned.

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Jan 21, 2025 12:47 PM in response to swipod touch

I have a Mac Mini M4 Pro and have seen the following. I have an external NVMe enclosure on the Thunderbolt port in the back. That drive stays connected!

I have another external enclosure with old HDD drives for my Time Machine backup connected on the back port via a USB-C to USB-B cable. That enclosure does NOT stay connected and I get a message every morning that my Time Machine was not ejected correctly.

I have moved it to the front port and so far it has been staying connected, but I will monitor for a few more days.


In summary I am experiencing USB 3.x devices on the back ports loosing connection. TB devices on the back ports remaining connected.

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Nov 23, 2024 7:32 PM in response to swipod touch

The rear-panel USB-C ports on the M4 Mac mini are multi-purpose ports that support

  • Traditional USB (I'm guessing at up to 10 Gb/s)
  • USB4 (up to 40 Gb/s)
  • DisplayPort
  • Thunderbolt 4 (up to 40 Gb/s)
  • [M4 Pro chip models only] Thunderbolt 5 (up to 120 Gb/s)

They adapt to whatever is plugged into them.


The front-panel USB-C ports on the M4 Mac mini are single-purpose ports that support

  • Traditional USB (up to 10 Gb/s)


You can think of the USB-C connector as being like the concept of a "Swiss Army knife", and the things that live on it as being like the "blades". Some Swiss Army knives have more blades than others; and some USB-C ports offer support for more types of things than others.

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Nov 23, 2024 7:10 PM in response to swipod touch

You're welcome.


To put it simply, the Thunderbolt ports on the Mac are a combination of high-speed data connection and power delivery, and it also carries compatibility with USB protocols. You can therefore use it to connect simple, less expensive USB devices to your Mac and the more expensive Thunderbolt specified storage, monitors, hubs and other devices. Killing two birds with one stone, as it were. That's why in descriptions, the ports are often labeled as Thunderbolt/USB. I agree that marketing could be better.

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Nov 23, 2024 7:17 PM in response to swipod touch

Sounds like the problem is how well USB-C sockets hold plugged-in cables, in general – rather than anything to do with Thunderbolt. I believe in this regards, the Lightning connector was a bit better than USB-C – even though the Lightning connector is not nearly as capable as USB-C.

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Jan 21, 2025 4:35 PM in response to swipod touch

Had the exact same problem.... now solved. The information herein might help others with troubleshooting.


I have an M4 Pro Mac mini and an Apple Studio Display. Have 2 Apple keyboards. One about 7 years old (Bluetooth) and another about 13 years old (Model A1243). Both have the numeric keypad. The older one has a USB-A connector.


I prefer the older Model A1243 just for the feel of the keys. But it would work intermittently when plugged directly into the Mac mini or the studio display (used Anker adapters). The front ports on the Mac mini worked best, but still were intermittent. Very frustrating.


Also have an OWC Thunderbolt-4 dock. Eventually plugged the dock into the Mac mini. This dock has a USB type-A port. This dock also comes with optional software for ejecting disks connected. But per OWC:


"When you install this app, a driver is also included for the dock’s high-power USB ports. The driver enables use of the Apple SuperDrive and USB Keyboard on these ports, and should enable them to charge 1st, 2nd, and 3rd generation iPads as well."


Installed the dock driver and plugged the old USB keyboard into the Type-A port of the dock. The keyboard works perfectly! I've been using it for a couple of weeks.


So.... I am wondering if the issue has something to do with the power (or voltage?) being provided through the new generation USC-C and/or Thunderbolt ports for old USB devices. Note that OWC dock has its own power supply.


Anyway, hope this info helps.

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Jan 23, 2025 10:18 AM in response to swipod touch

Had two USB drives plugged into rear USB-C ports, one an SSD with a short cable (USB-C to USB-C) used as Time Machine BU, the second was a USB-A through a USB-A to USB-C pigtail with an extended, longer USB cable to the 2nd disk drive. The OS was flagging dismounts with the TimeMachine drive. When I moved the 2nd cable to the front USB-C, the dismounts with the still rear attached TimeMachine SSD went away. IMHO the rear connectors are underpowered to be fully utilized.

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Jan 23, 2025 4:39 PM in response to hcsitas

Well, since you posted the incorrect cable to use, and I did ask how you decided the cable was the problem when it works 100% in the front, I guess you have no reasoning for thinking it's the cable since I asked politely for you to explain your thinking and you just bailed.

If it works in the front but not in the back, even a noob can conclude it's obviously not the cable - you don't need 3 decades of experience to figure that simple situation out.

Thanks for trying, but nothing you said made sense, yet I did ask for your explanation, which you balked on.

Good luck out there

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Jan 18, 2025 10:05 PM in response to azurmaraces199

Sleep is unnecessary on later Macs and should be disabled. Shut for long absences/idle overnights and for regular operation use the settings exactly as shown below: (reboot after setting):


Also, do not manual-sleep for brief absences; use instead the Lock Screen settings to switch the display off on timer:


Once set, you can also use Control-Command-Q to immediately lock your screen (instead of waiting for the display to switch off on timer).

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USB problem/Thunderbolt on Mac mini M4

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