USB problem/Thunderbolt on Mac mini M4

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.

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.

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.

Update - Replaced the long USB extender cable with adapters with a single "high speed" USB-C to Micro-B Cable (no adapters) and have been using the rear ports without "disconnect" error for a few days.

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).

The last thing I'm going to check is to see if the insecure fit problem also exists with an Apple-branded Thunderbolt cable (iow, if the Mac Mini M4 doesn't play nice with non-Apple cables). I have a nearby Apple store, so probably will just take it in to have them see for themselves.

I'd suggest giving your cable the jiggle test to see if the physical port is the problem.

(*I haven't messed with the 3rd rear port because my Home directory is running on an external drive there; it also disconnected once, causing problems, and I'm leaving it untouched with my fingers crossed).

I had the same problem on new mac mini m4 : 1 apple keyboard and 1 optical mouse, both wired and fitted with a simple usb to usb-c adaptor, and connected to any of the front usb-c or rear thunderbolt slots had them disconnected after a while. Using a non-powered usb hub didn't change this.

After lots of tryouts the following works (but don't ask me why) : optical mouse connected to front usb-c slot and apple keybord connected to a non-powered hub connected to rear thunderbolt port. Doesn't work without the hub !

See hardware usb values included

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.

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.

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.

I have a related problem. I just migrated to the Mini M4 from a 2015 iMac, and my backup protocol involves old HDD/SSD disk enclosures with USB connectors.

These work fine when plugged into the front USB-C ports (with adapters where required).

The same disks fail to mount when plugged into the rear T-4 ports.

Am I doing something wrong, or just not understanding the interoperability?

All of the USB-C ports on a M4 Mac Mini or M4 Pro Mac mini - front or back - should support USB 3 devices.

The rear-panel USB-C ports are the only ones that also support USB4, DisplayPort, and Thunderbolt. So normally the issue would be that you tried to plug something into a front-panel port that needs a protocol only available in the back. (Like a display or display adapter; or a hub that has both HDMI and USB-A ports.)

If USB-C to USB-A adapters work

in the front, but not in the back, I’d suspect that some piece of equipment was not standards-conformant. I couldn’t say whether that would be the TB4 ports or the adapters, but if they are third-party adapters, you might want to try a different brand. I’m guessing that Apple tests interoperability a bit more than third-party adapter vendors might.

Thanks, Servant of Cats.

Alas, I have just one Thunderbolt-compatible peripheral – the case for my external SSD (which does the heavy lifting alongside the 256GB internal). Also, my problem is the reverse of what you have mentioned. The drives are working fine in the front (USB-only) panel ports, but not in the rear (USB++) ports.

Hi,

I have kind of the same problem. My external ssd mounted at the back of my Mac mini M4 works fine. All other ports do nothing. I received the mini from apple on Monday. I'm a bit stuck now.

The cables and such that I use all worked fine on my old iMac.

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.