Mac Mini 2018 USB-C port issues

[strawbale]

Been using one of these ports (with a USB-C to micro-USB-B cable to my WD ext HDs) for years to do weekly backups.
Suddenly, now, these mains-powered ext disks are not any more 'seen' (not in Finder nor in Disk Utility) by any of the Mac Mini 4 ports.
However, when using the same cable with the USB 2.0 port of my wired keyboard (that is plugged in the USB-A ports of the Mac Mini), it DOES work. And testing the Mini's USB-C ports with a USB-stick all 4 ports work fine too.

So it seems these 4 ports, suddenly, all still work for data transfer unless that's an ext HDD, even though these ext HDs are mains-powered?

Any ideas are most welcome!

PS: Another issue seems to show up at the same time: when logging in I cannot type in the password box at first, after a seconds a window comes up saying that it's looking for a bluetooth keyboard (which I don't have), the window then disappears, and only then I can type my password 🤷‍♂️

 

[DeltaMac]

So, you are saying that the external HD won't mount when plugged directly into a USB port on your mini-- but, the HD will mount (allowing data transfers) when plugged into a USB port on your wired USB keyboard?

 

[strawbale]

So, you are saying that the external HD won't mount when plugged directly into a USB port on your mini-- but, the HD will mount (allowing data transfers) when plugged into a USB port on your wired USB keyboard?

Yes, but using different Mac Mini USB ports:
plugged directly NOT working with any of the Mac Mini's four USB-C ports; plugging indirectly (via my wired keyboard) using the Mac Mini's USB-A ports it DOES work.
PS: I didn't test directly into the Mac Mini's USB-A ports (as then I'd have to unplug my wired keyboard), but I assume that'd work too.

 

[strawbale]

I've tested with two different cables, the ones that have always been working.

Does an external HD, even a mains-powered one, need a powered connection with the Mac Mini?

 

[DeltaMac]

The USB port on your wired USB keyboard is not powered...

Looking back at your first post... Seems like you don't have ANY USB at first (you couldn't type on your USB keyboard, then get the "searching for keyboard" (your Mac would then be searching for ANY keyboard, it's normal for it to search for a bluetooth, when no USB keyboard is detected, even if you have never used a bluetooth keyboard. That's normal when no other keyboard is detected.
So, your Mac mini is simply slow to boot, and slow to detect (and connect to) USB devices. Something is not working correctly.
What OTHER devices do you normally have connected to your mini, on ANY port, including any external USB hubs, other external networks/Ethernet cables?
What macOS system are you using now? Have you updated to the current macOS 26 (Tahoe)?

 

[strawbale]

Thanks for getting back to me - much appreciated!

Normally only the monitor, through the hdmi port, and a printer, through the keyboard port (as it's I don't have a USB-C to USB-C printer cable). Occasionally a USB-stick.
It's my wife's computer, hardly used as she prefers her iPad mini. I use it occasionally as we've got MS Office on it (and not on my M1 Mc Mini).
Just tried printing with using the USB-A to USB-B printer cable and an USB-C to USB-C adapter in one of the Mac Mini's USB-C ports and that works fine, like the USB sticks did work fine in there.
I may have somewhere a powered as well as an non-powered USB-hub which I could try.

 

[strawbale]

Update: with (mains-powered) ext HD connected to a Mac Mini's USB)C port via a mains-powered USB-hub it DOES work. (without the mains-power of that hub it does NOT work).

 

[DeltaMac]

Might be helpful to run the built-in diagnostics on the mini.
This link should help with that...

Can you tell me what version of macOS is running? "About this Mac", in the top left corner of your screen, top item in the Apple menu will show the operating system version that you are using.

 

[strawbale]

Might be helpful to run the built-in diagnostics on the mini.
This link should help with that...

Can you tell me what version of macOS is running? "About this Mac", in the top left corner of your screen, top item in the Apple menu will show the operating system version that you are using.

15.7.1

I'll try that link - thanks! (later)

 

[strawbale]

That links start internet recovery - is that what's needed?
I haven't chosen a language yet, like to know of I should proceed.
Googled what this does, so did proceed.

Diagnostics ran offline :
There may an issue with the Thunderbolt hardware
Disconnect external Thunderbolt devices and run the test again. If you get this message again click get started below

Which I did. Seems trying for ever to connect to start internet MacOS recovery (?)
Doesn't seem to be able to connect through wifi nor ethernet nor personal hotspot 🤷‍♂️

For the moment will (have to) continue to use one of the two workarounds: via wired keyboard or via mains-powered USB-hub

 

[strawbale]

Update: when turning off Bluetooth (and thus using a wired mouse), the problem does NOT exist.
Is this interference something since 15.7.1 ? (the 2018 model can't run 26)

 

[DeltaMac]

Diagnostics does not really use an internet connection (but may need to be connected, if possible)
I would suggest trying that diagnostics again, but no external devices, except your USB keyboard/mouse
Also, if you have one, a USB to ethernet adapter, plugged in to your internet. Your goal with this, is to get a results code, when the dignostics complete.

 

[LionTeeth]

I run two SSDs and had one powered spinner. The hard disc spinner was always having problems being seen. Always. Seven years of oh no it's not mounted again argh.
I retired it recently and the SSDs continue to be rock solid, never a single issue. Good riddance to the disc. I feel your pain OP. This model Mac is so finicky.

 

[strawbale]

Diagnostics does not really use an internet connection (but may need to be connected, if possible)
I would suggest trying that diagnostics again, but no external devices, except your USB keyboard/mouse
Also, if you have one, a USB to ethernet adapter, plugged in to your internet. Your goal with this, is to get a results code, when the dignostics complete.

The code I get after running diagnostics is NDT001:

"There may be an issue with the Thunderbolt hardware.
Disconnect external Thunderbolt devices and run the test again.

If this code appears again, further troubleshooting may be required. Contact Apple or take your computer to an AASP or Apple Store to learn which service and support options are available."

As the tests I've done since, see above, I think there is an interference between Bluetooth and the Thunderbolt/USB-C, because disable Bluetooth get rid of the issue. (not a solution for my backups, but good to know that works)

Then I read LionTeeth's post and tested, with Bluetooth on, an external SSD (T7) with its own, very short, cable: that worked fine!

As said before, ext HD via keyboard into Mac Mini's USB-A ports works, and ext HD via mains-powered USB in Mac Mini's TB/USB-C ports works too.

Conclusion:
There's 'only' an issue when, with Bluetooth ON, the ext HDs are plugged directly into the Mac Mini's TB/USB-C ports.
Unfortunately that's my user's case

A case of badly shielded cables in combination with Bluetooth?

Mac Mini (2018) - WiFi / Bluetooth problem - Apple Community

discussions.apple.com

Shielding Resolves USB 3.0 Conflict with Bluetooth

We set out to find a resolution to the problem - one that fixes things not just for the miniStack, but for all USB 3.0 drives used with a Mac mini.

eshop.macsales.com

But why now, 7 years after having worked fine?

 

[DeltaMac]

New, unusual hardware problems? Why would you suddenly start having strange problems after more than 7 years of mostly working OK?
You have a battery, which, if low voltage, or maybe completely dead, can begin causing odd problems. I sometimes will use a simple replacement of the RTC battery as a troubleshooting step. I used the word "simple", but you have to completely remove the logic board to get at that little BR2032 battery-- just something to think about if you continue to have problems.

 

[Fishrrman]

These are all WD external platter-based HDDs, each with it's own "power block"?

And you've had them "for years" ??
Could the power supply blocks be failing on you?
Could the connections between power supply and drive be getting flaky?
Have you tried swapping the power blocks around?

This is suggested because you mention that when you connect the drive to a powered hub, it will then mount. I'm thinking that even though the power supply may be faulty, the drive is somehow getting the power it needs to spin up and "be ready" from the hub's bus power.

Here are some seemingly off-the-wall suggestions.
They will hurt nothing, so I recommend you try them.

1.
Power down the Mini, all the way off.
UNPLUG it from the wall outlet for about 5 minutes, then plug it back in and reboot.

2.
Get logged in and into the finder.
Disconnect all external drives.
Open System Settings.
Go to "users & groups".
Now, create a NEW user account. Give it administrative privileges. Use any name and password you wish, this is only a "test account" (it can be deleted later if you want).
Once this is done, try RE-mounting the drives one-at-a-time.
Any difference?
(I suggest this just to eliminate any possibility that something in your user account may be affecting things. Unlikely, but... you never know.)

How OLD are these drives?
If more then, say, 7-8 years old, might be time to start thinking about replacements.
You can get good SSDs these days for not-a-lot of money...

 

[strawbale]

These are all WD external platter-based HDDs, each with it's own "power block"?

And you've had them "for years" ??
Could the power supply blocks be failing on you?
Could the connections between power supply and drive be getting flaky?
Have you tried swapping the power blocks around?

This is suggested because you mention that when you connect the drive to a powered hub, it will then mount. I'm thinking that even though the power supply may be faulty, the drive is somehow getting the power it needs to spin up and "be ready" from the hub's bus power.

Here are some seemingly off-the-wall suggestions.
They will hurt nothing, so I recommend you try them.

1.
Power down the Mini, all the way off.
UNPLUG it from the wall outlet for about 5 minutes, then plug it back in and reboot.

2.
Get logged in and into the finder.
Disconnect all external drives.
Open System Settings.
Go to "users & groups".
Now, create a NEW user account. Give it administrative privileges. Use any name and password you wish, this is only a "test account" (it can be deleted later if you want).
Once this is done, try RE-mounting the drives one-at-a-time.
Any difference?
(I suggest this just to eliminate any possibility that something in your user account may be affecting things. Unlikely, but... you never know.)

How OLD are these drives?
If more then, say, 7-8 years old, might be time to start thinking about replacements.
You can get good SSDs these days for not-a-lot of money...

The same (two) ext HDs (for backups only, once a week) continue to work fine with my mac Mini M1, using the same cables, also using the TB/USB-C ports. The position in relation to the (shared) wifi/ethernet router is slightly different, which may or may not play a role (according to the above link on shielding issues).

The WD My Book 4TB is 4yr old (but only used once a week for backups), the WD Elements Desktop 4TB is 5yr old (same usage). I need these sizes as it holds backups of the two mac Mini's and a 2GB external HD data disk (photos and music), so SSDs a bit expensive for 'just' weekly backups, no?

The fact that things work fine with the same USB-C to micro USB-B cable VIA the USB2.0 keyboard to the USB-A ports of the Mac Mini, with our without Bluetooth on, implies there's an issue with the TB/USB-C ports (and not with, e.g., the ext HD power supplies - who are on the floor)

The fact that using these cables directly into the TB/USB-C ports with Bluetooth OFF, but not with Bluetooth ON, implies there's a Bluetooth interference with the RB/USB-C ports.

Why with the Intel 2018 MM and not with the M1 MM - maybe the position of the ext HD in relation to the MM and the 4G router? 🤷‍♂️

Why NOW, after 7 years for the MM 2018 and 4-5 years for the ext backup HDs? 🤷‍♂️🤷‍♂️

 

[strawbale]

For the moment, until knowing what the real cause (and solution) is, the two simplest workarounds I have:

* either plugging the cable into the wired USB2.0 keyboard (and losing transfer speed)
* or plugging the cable directly into a TB/USB-C port AND temporarily switching off Bluetooth AND (thus) a wired mouse (into the keyboard)

As it's 'only' for the weekly backups, it's OK (for the moment)

There is the third workaround of using a mains-powered USB hub, but that seems a bit cumbersome for 'just' this weekly issue.