I've had some issues in the past couple of years with external HDDs and sleep/wake functions. That's with an M1 Max Studio. Never had disconnection problems though. Using the Mac app Amphetamine has worked pretty well in situations where I need the HDDs to run smoothly without suddenly going to sleep and/or having issues with waking.
I don't have this issue with my M4 Mac Mini. I have an old Apple wired keyboard (A1243) with a crappy Dell wired mouse attached to it. The keyboard is then plugged into the front USBC port using a Ugreen USB hub (model:CM478). I have two monitors connected using the rear HDMI and USBC ports.
I am on Sequoia 15.1. 24Gb RAM and 512Gb storage.
This is my Energy settings.
I hope this helps others with their issues.
Yup, that’s the first place to start looking with USB issues that pop up during waking up your computer from sleep and even with certain energy saving features that kick in under certain conditions. I’ve see USB issues related to sleep and energy settings on not only Macs but Windows PCs as well. I remember one model of Dell laptops more than 15 years ago that required changing BIOS settings to keep the USB ports powered up when the computer went into energy saving modes. They are even more prevalent if you’re using a dock or hub, whether the dock/hub is connected via USB or Thunderbolt. I see this issue occasionally on USB thumb drives and SD adapters connected to USB ports on a TB3 hub on my M2 MacBook Air. Don’t forget that most wireless peripherals have their own power saving and sleep features too and those features can contribute to the problem.
The USB protocol does have heartbeat/keep-alive like features to ensure the communication between the hub and connected devices is maintained when there is no traffic between them. These features (as of USB3) are power-saving aware and the bus can enter a suspended state after a period of no traffic. Connected USB devices that support these features are expected to periodically wake up and let the host know they are still there when they haven’t been using the bus for a while. The mechanism works differently on pre-USB3 compared to post-USB3 especially for low power features. When the host and device initiate a connection they negotiate all of the required bus settings for both ends including speed, power, polling rates (mice and keyboards), and suspend/resume timing. In theory there should be no issues at all once the connection is established. But that assumes both ends work correctly and there are no wiring or electrical issues.
Multiple hubs, SSD drives, multiple cables from different manufacturers all hooked up into a menagerie of additional wires and cables and peripherals what could go wrong? Apple M2 Ultra Studio owner, no hub/external SSD drive user. Hopefully there is a software upgrade fix. I doubt it. Speaking of which Bluetooth has is always flaky…..
USB-C on my fist iPad Pro with it eventually failed, got too loose to be able to charge. Had to replace it despite working fine otherwise. Lame. Never had this problem with Lightning
M4 512 Mac mini HDMI 27’ and USB-C 32’ set to energy saving on wake up the 32” will not pick up the signal and requires on/off to get an active screen. Been doing this since day one, swapped USB cables, altermnated HDMI connections, so it was then the 27” which didn’t start.
Both front and rear USB-C ports have been swapped..makes no difference.
so I just switch off screens, then on and no further issues..
It’s annoying though and consistent with other comments. I hadn’t thought of ‘low energy’ setting though..that was in a previous comment I read in this forum today….
M4 512 Mac mini HDMI 27’ and USB-C 32’ set to energy saving on wake up the 32” will not pick up the signal and requires on/off to get an active screen. Been doing this since day one, swapped USB cables, altermnated HDMI connections, so it was then the 27” which didn’t start.
Both front and rear USB-C ports have been swapped..makes no difference.
so I just switch off screens, then on and no further issues..
It’s annoying though and consistent with other comments. I hadn’t thought of ‘low energy’ setting though..that was in a previous comment I read in this forum today….
I recommend installing BetterDisplay trial version on your Mac mini. This app allows you to configure all of settings on monitors without having to mess around with the tedious on screen display (OSD). It will work with all connection types, for example, HDMI, DisplayPort, etc. The USB-C connected monitor is probably using DisplayPort 1.4.
Once you get access to all of the settings look for anything related to Signal Detection, wake-up, and sleep settings for the USB-C connected monitor. On the HDMI monitor look for HDMI CEC settings, and anything related to sleep or wake-up detection when the computer wakes up.
I use BetterDisplay primarily to switch between monitor video inputs when I have multiple computers or other HDMI devices like Apple TV connected to the same monitor. But BetterDisplay also gives you access to nearly all settings in monitors including Studio Display monitors.
I have an M4 mini and an external SSD that disconnects when plugged into the back ports but works fine in the front ports. It's a Kingston Fury M2 4TB "disk" in an ASUS TUF Gaming A1 enclosure. The enclosure gets quite hot even when the disk is idle so it must draw quite a lot of power. When I test the disk with Blackmagic Disk Speed Test it works fine while writing, but disconnects as soon as it starts to read.
Seems to be a M4 mini issue and is not one for the M4 Pro mini. No issues with my M4 Pro mini that has the Studio Display and an OWC raid attached on the rear USB-C 5 ports. During the Migration System work, an Apple Magic Keyboard was plugged into a front port as Bluetooth was not yet operational.
Long story short, I'm thinking there are 2 issues going on here. The first is Mac OS Sequoia; definitely don't install it on your M1 systems. The second being the TB5 ports on the M4 Mac Mini, don't buy it until Apple acknowledges this and has a fix. These issues are also cropping up on their newer M4 Mac Studios from what I have read on various forums.
I manage several computers for home & our church. I was waiting for the M4 systems to replace my 2010 Mac Pro with the Mac Studio and my 2012 27" iMac with a Mac Mini & monitor. After purchasing an M4 Pro Mac Mini to replace my iMac, its is the first Apple computer in 20+ years I wish I had never bought due to the position of the power switch, the Sequoia version of Mac OS, the back TB5 ports, and the very poor and noisy heat management system.
Out of the box, the M4 Pro Mac Mini had issues with any USB 2 device that was plugged into them; drive, keyboard, or mouse. The first issue was during the initial OS update. All the USB C & TB5 ports were dead toward the end of the update. I couldn't get the keyboard or mouse to work in any port, front or back. Computer had to be shutdown holding down the power key. Fortunately, it continued where it left off and came back. Keyboard now worked in the front USB ports, but not the back.
Second issue, once the initial setup was done, was no USB device with a USB A type of connection worked in the rear USB ports. USB C drives worked ok, but may or may not connect/mount. This was Mac OS 15.1.1 Computer is currently running Mac OS 15.3.2 Most of the issues seem to have been resolved except USB 2 devices plugged into the back TB5 ports. They mostly work, but may not be available at times. Seems like the ports are turned off and the keyboard isn't enough to wake them up? Keyboard has to be plugged into a front port.
Prior to getting the M4 Mac Mini, I had done an OS upgrade to Mac OS 15.1 on the following computers and had the issues on all of them.
M1 Pro 16" MacBook Pro: Right TB4 Port Not Working
M1 2020 Mac Mini: USB A Ports Unreliable Connections
M1 2020 Mac Mini: USB A Ports Unreliable Connections
Note that for the issues below, for the most part, these are direct connections to the computer's ports. Only exception was USB A devices on the MacBook Pro used a simple dongle to go from USB A to USB connections. Dongle is working correctly at USB 3.2 speeds.
On the MacBook Pro's TB4 port, drives would show up in disk utility however, they would not be mounted in Finder. I chatted online with Apple and was unable to resolve this issued. It was recommended to re-install the OS. Did that erasing the SSD first and installing Mac OS 15.1.1 which had just been released. Same issues without any additional software installed and nothing from the previous installation copied over. Problems continued with the Mac OS 15.2 update.
On the Mac Minis, USB 2 or USB 3 drives wouldn't connect all the time and if they did, they may disappear while you are accessing them. These were various drives formatted with the FAT32 or EXFAT file systems. We had one drive that when plugged in, crashed the computer. All you got was the spinning beach ball. No keyboard, no mouse, only option was the power button. I plugged the drive into a linux system, it worked fine and found out it was formatted with the NTFS file system.
Note that none of the problems on the older M1 systems existed before the the installation of the Sequoia version of Mac OS. They were all running Mac OS Monterey 12.6.2 before and working fine including the NTFS formatted drive.
The current state is that the M1 systems are reverted to Mac OS Sonoma 14.7.3 which resolved all of the USB issues.
Being an electronics engineer, I've been using all types of computers and operating systems since the 80's. We shouldn't be having any of these issues from Apple, or anyone else. The main reason I switched to Apple computers was because they just worked. With the M4 & Sequoia, that seems to no longer be the case.
I wonder if it's the M4 or just the M4 Pro mini. The M4 Pro has thunderbolt 5 Ii may be a negotiation problem between me older versions and thunderbolt 5.
I have had zero USB problems with my M4 Mac mini pro, and I have a (metric) crap-ton of USB devices plugged into it. This includes a KVM switch to toggle back and forth between the old (2018) and new (M4 Pro) Mac minis with 3 peripherals attached. The new Mac mini also does much better with the external drives than the old one did, giving pretty much their rated performance whereas the old one could never quite get there.
I’ve been holding off purchase of an M4 Mini (not Pro).
I currently have an M1 MacBook Air and use a CalDigit TS4 dock to connect all peripherals…monitor (DP), USB-A (some are only USB 2) and USB-C (all USB 3, either 5 or10 Gbs) connections. Other than the cable to the laptop I have no TB devices connected of any kind on a regular basis. I have been able to successfully mount a TB2 SSD using the Apple adapter, but I have never left it connected after transferring files. I’m still running Sonoma.
My idea was to plug the TS4 into the M4 Mini and keep everything else connected to the TS4 as it is today.
I keep reading these horror stories since shortly after the M4 Minis arrived and I’m worried for two reasons:
1. For a brief while I was getting drive disconnects, this stopped once I started shutting down the laptop from 10PM to 7 AM every day. I was worried about the disconnects causing disk errors, but after running First Aid all seems to be OK
2. I’m still using Sonoma. I only update the OS when I need to and (don't laugh) the usual reason is when Intuit informs me I need to update my OS in order to run Turbotax for the next tax year. I prefer to not update an OS until just before the new OS drops in the fall. I figure that way most of the buggy behavior will have been fixed. I’m assuming that if I buy a new Mini it will come with Sequoia and I won;t be abel to back up to Sonoma. Plus OS 26 is about to drop. Ugh.
I read that some users have had no issues. Obviously the people who do have issues will be vocal about them. Those who don’t have issues may not know that anybody is having issues. So…is it safe to buy an M4 Mini or not?
This is an update to my "March 24, 2025 2:17PM" post and a reply to Enossified's post from "June 11, 2025 5:41PM".
First is an update. Most of the USB issues I was having on the Mac Mini with M4 Pro have been resolved somewhere in the 15.4 or 15.5 updates. Ejecting discs can still be slow. This appears to be finder not being updated of the disc's connection status as restarting finder will show the disc is not mounted.
After reading about this issue on other forums, the TB5/TB4/USB-C ports appear to have limited power and do not support the full expected power rating for each port when all the ports are used. This appears to have been the case for a while, i.e. not just an M4 issue. I currently have a externally powered disc/hub to the middle TB5 port. Keyboard is plugged into the one front USB-C port and an unpowered USB-A hub into the other front USB-C port.
I'd go ahead and buy what you need. I'm going to need to replace my 2010 Mac tower and will do it with the M4 version of the Mac Studio-which also appears to the power limitations on the back TB5 ports. With the Mac 0S 15.5 update and not trying to draw too much power out of the TB5 ports, things should work well.
Still not sold on Mac OS Sequoia and would downgrade if I could. However, the apps I use seem to work well so far; Final Cut Pro, GIMP, Inkscape, Keynote, LibreOffice, Logic, Numbers, Pages, Sound Studio, UVR, & Topaz photo & video apps.
Comments
The USB protocol does have heartbeat/keep-alive like features to ensure the communication between the hub and connected devices is maintained when there is no traffic between them. These features (as of USB3) are power-saving aware and the bus can enter a suspended state after a period of no traffic. Connected USB devices that support these features are expected to periodically wake up and let the host know they are still there when they haven’t been using the bus for a while. The mechanism works differently on pre-USB3 compared to post-USB3 especially for low power features. When the host and device initiate a connection they negotiate all of the required bus settings for both ends including speed, power, polling rates (mice and keyboards), and suspend/resume timing. In theory there should be no issues at all once the connection is established. But that assumes both ends work correctly and there are no wiring or electrical issues.
set to energy saving
on wake up the 32” will not pick up the signal and requires on/off to get an active screen.
Been doing this since day one, swapped USB cables, altermnated HDMI connections, so it was then the 27” which didn’t start.
Both front and rear USB-C ports have been swapped..makes no difference.
so I just switch off screens, then on and no further issues..
It’s annoying though and consistent with other comments.
I hadn’t thought of ‘low energy’ setting though..that was in a previous comment I read in this forum today….
When I test the disk with Blackmagic Disk Speed Test it works fine while writing, but disconnects as soon as it starts to read.
Testing the Mini as my primary workstation at work. Been using for about a week-and-a-half.
Have lost the display about 3 times now.
I currently have an M1 MacBook Air and use a CalDigit TS4 dock to connect all peripherals…monitor (DP), USB-A (some are only USB 2) and USB-C (all USB 3, either 5 or10 Gbs) connections. Other than the cable to the laptop I have no TB devices connected of any kind on a regular basis. I have been able to successfully mount a TB2 SSD using the Apple adapter, but I have never left it connected after transferring files. I’m still running Sonoma.
My idea was to plug the TS4 into the M4 Mini and keep everything else connected to the TS4 as it is today.
I keep reading these horror stories since shortly after the M4 Minis arrived and I’m worried for two reasons:
1. For a brief while I was getting drive disconnects, this stopped once I started shutting down the laptop from 10PM to 7 AM every day. I was worried about the disconnects causing disk errors, but after running First Aid all seems to be OK
2. I’m still using Sonoma. I only update the OS when I need to and (don't laugh) the usual reason is when Intuit informs me I need to update my OS in order to run Turbotax for the next tax year. I prefer to not update an OS until just before the new OS drops in the fall. I figure that way most of the buggy behavior will have been fixed. I’m assuming that if I buy a new Mini it will come with Sequoia and I won;t be abel to back up to Sonoma. Plus OS 26 is about to drop. Ugh.
I read that some users have had no issues. Obviously the people who do have issues will be vocal about them. Those who don’t have issues may not know that anybody is having issues. So…is it safe to buy an M4 Mini or not?
This is an update to my "March 24, 2025 2:17PM" post and a reply to Enossified's post from "June 11, 2025 5:41PM".
First is an update. Most of the USB issues I was having on the Mac Mini with M4 Pro have been resolved somewhere in the 15.4 or 15.5 updates. Ejecting discs can still be slow. This appears to be finder not being updated of the disc's connection status as restarting finder will show the disc is not mounted.
After reading about this issue on other forums, the TB5/TB4/USB-C ports appear to have limited power and do not support the full expected power rating for each port when all the ports are used. This appears to have been the case for a while, i.e. not just an M4 issue. I currently have a externally powered disc/hub to the middle TB5 port. Keyboard is plugged into the one front USB-C port and an unpowered USB-A hub into the other front USB-C port.
I'd go ahead and buy what you need. I'm going to need to replace my 2010 Mac tower and will do it with the M4 version of the Mac Studio-which also appears to the power limitations on the back TB5 ports. With the Mac 0S 15.5 update and not trying to draw too much power out of the TB5 ports, things should work well.
Still not sold on Mac OS Sequoia and would downgrade if I could. However, the apps I use seem to work well so far; Final Cut Pro, GIMP, Inkscape, Keynote, LibreOffice, Logic, Numbers, Pages, Sound Studio, UVR, & Topaz photo & video apps.