USB problem/Thunderbolt on Mac mini M4

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.

I'm new to Mac. Recently bought a Mac Mini with M4 chip. My problem is with the front ports (not the rear ports). I have an XCellon USBC-4311-2 hub and a wireless Logitech mouse. The mouse stopped working. Switched the hub to one of the back ports and the mouse worked again. After rebooting, the the front ports started working again. Took the computer to a local authorized dealer. They ran some checks and they say all is fine. Today it happened again.

I have similar issues. Keyboards and mice plugged into the back Thunderbolt ports on my M4 mini will randomly stop working, requiring a physical disconnect and re-connect. These are native USB-C connector devices; I'm not using USB-A to USB-C converters.

Looks like these back ports are becoming a fairly well known issue, based on just a few minutes' web searching.

Hopefully fixable by a firmware or OS update!

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.

The main value of the article is confirmation that more that four of us are having issues in the regard :)

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.

Definitely not a cabling issues, it is the Mac Mini. I used the link to submit a bug report.

see my previous post for link to Mac World article.

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.

Update 2 - after replacing both cables with short, direct connectors….. I thought I nailed it but I was wrong. The SSD TimeMachine drive still threw Illegal Dismount Errors. The USB drive with a hard disk however, didn't. I think it has to do with the SSD drive getting it's power through the USB-C Port. I have moved the SSD connection to the front of the Mini M4 and haven't seen a Dismount Error since. I ordered 2 right angle connectors so I can route the cable along the side of the Mini, otherwise it looks dorky to have a cable poking out the front.

It’s actually the USB consortium that’s confused everyone. A Thunderbolt cable whether 4 or 5 is certified by Intel to meet the spec, so that means all USB standards up to USB4 (Tbolt 3 cables support USB 3.2).

USB cables are not certified and often not even marked. Look at the charging cable that came with your recent MacBooks…C to C, no markings and it only passes power, no data.

To figure out what a USB C-C (or C-A, C-B, etc.) cable can support I connect a peripheral using that cable and see what System Report displays for the USB connection. The cable that came with my Samsung T7 shows 10 Gbs rate, which is 3.2 gen2 as advertised. I have other USB-C cables that when used with the T7 show only 5Gbs data and one that shows only a USB 2.0 connection!

So when I need spares or something longer, I’ve bought TB4 cables. At least I know they will provide the maximum speed and power for any USB peripheral I might use.

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).

I agree no modifications should be necessary, a USB C connection alone should be secure, but I am finding the same thing, very lose, and any touch causes a connection break.

should I return it?

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.

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

BerkeleyBernie wrote:

I think it is a physical hardware problem in my case— the rear ports do not provide a secure fit. Slight movement of a cable is enough to disconnect an external drive. In my case, I have a powered OWC 11-Port Thunderbolt Dock (with 2 drives attached) connected to a rear port. I've now tried 2 thunderbolt cables to connect the dock to the rear ports on the M4 Mac Mini and I've tried 2 of the 3 ports.* Both cables and both ports have disconnected with a slight movement of the cables (at the Mac Mini end of the cable). Both cables are new that came with products (i.e. external drive enclosures).

It shouldn't be necessary to use something like this. I haven't found it necessary on my Mac, and have no idea how well this gadget works – but in case the link is helpful:

Other World Computing – OWC ClingOn USB Type-C Connector Securing Device