While the new M4 Mac mini has impressed us all with its small size and processing prowess, a USB-C connectivity problem has been baffling many early adopters.

As spotted by AppleInsider, posts on several different forums by people who bought the Mac mini but have issues with connected USB-C devices. In many instances, the devices stop working or don’t work at all. Posts have appeared in the Apple Support Community, MacResource, and Reddit. The issue doesn’t appear to affect any of the other M4 Macs that were released at the same time.

One pattern that appears from the various postings is that users are connecting USB-A devices by using a USB-C adapter on a rear Thunderbolt/USB-C port. They experience inconsistent connectivity, but once they switch to a front USB-C port, the devices work properly. Some users report problems with devices that draw power from the rear ports. In some cases, disconnecting the device and then reconnecting it fixes the problem.

The M2 Mac mini had a pair of USB-A ports but Apple removed them when it redesigned the Mac mini with a smaller design, hence the need for USB-C-to-USB-A adapters.

The problems seemingly don’t affect the Mac mini’s front ports, which are USB-C only and not Thunderbolt ports. This could be a sign of a problem between adapters communicating with the multi-purpose nature of the rear ports. The adapters could be inadequate at maintaining the signal that the rear ports require for making a connection.

Apple has yet to comment on the issue. If you do need to use a USB-A to USB-C adapter to connect a device to a Mac, rely on products made by reputable companies, such as Apple’s own offering. It’s easy to find cheap adapters on Amazon from companies with nonsensical-sounding names, but in our experience, it’s worth the few extra dollars to invest in products from known companies. Check out our guides on the best USB-C hubs and adapters and the best Thunderbolt and USB-C docking stations.