Mac mini 4 Usb-c display Port issues.

Question

Mac mini 4 Usb-c display Port issues.

I am currently running the latest OS Version and I am trying to get a multi monitor setup on a kvm running.

The first time I connect the cables, starting with the USB-C to dp and then the hdmi cable I have no issues. As soon as I switch to my work computer and back or the Mac locks the screen, I don't get the USB-C monitor signal properly and the connection drops every second.

Another odd issue is that even when things work, sometimes the USB-C monitor flickers and then the refresh rate drops from 165 hz to 144hz to 120 and then to 100 until I am stuck at 60hz. I can't change it back to the original 165hz.

If I unplug the USB-C and hdmi cables on the Mac Mini and connect them again it works again.

The kvm supports dp 1.4 and hdmi2.1 and as mentioned, I have to right cables and switched them.

The kvm works fine with 4 different computers on the same port and I already switched cables to no avail. The issue only occurs on the Mac Mini m4 Usb-c display.

Posted on Aug 4, 2025 1:38 PM

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Answer 1

Sep 16, 2025 6:45 PM in response to Just_asking_questions

Macs do not depend on packages of display "drivers" (tables of settings) like Windows does.

They go straight to the monitor and ask the monitor (the definitive source) about what settings it supports. This only happens at certain times, and it seems possible that if you are using a KVM to switch connections out from under the computer, that the Mac doesn't know that things have changed and that the display should be queried again.

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Answer 2

Sep 16, 2025 5:27 PM in response to Just_asking_questions

Could it be power settings on the M4, like the device going to sleep after a couple of minutes? Keyboard and mouse also coming in through the same Usb-c of the display?

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