External drive on iMac M1 not connecting via thunderbolt 4 port

I have an external drive that supports thunderbolt 3. When I connect it to one of the thunderbolt 4 ports on my iMac M1 (four usb port model) it doesn't mount and I don't see anything in Finder. However, when I connect it to one of the USB 3 port it works fine. I've checked the cable and it supports thunderbolt 4 and I even replaced it with a new one. Any suggestions as why the thunderbolt 4 ports aren't working as expected?

iMac (M1, 2021)

Posted on Aug 27, 2025 06:48 AM

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External drive on iMac M1 not connecting via thunderbolt 4 port

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