Macbook M4, 2nd monitor STOPPED working after a month

MacBook Air 15-inch, M4, 2025, 32GB, Sequoia 15.4.1

Monitor 1: LG 34WL500 via Anker USBC to HDMI.

Monitor 2: LG 24MP60VQ via Anker 5-in-1 Hub with generic HDMI to HDMI cable to monitor.

I have been using my new Macbook with two external monitors for a few weeks. This afternoon I came back from lunch and the second monitor says "Choose to Mirror or Extend Display from the [display] menu." I go to the Display in System Settings, and the 2nd monitor does not even show up as an option. Only the Built in Display and the Monitor 1 (LF HDR WFHD) are options.

When I restart the computer, it will send a signal to the 2nd external monitor (I can see the desktop pic), but when it starts up again, I get the message above.

I just switched the cables at the back of the monitors, and they both worked, but the 34" was laggy and didn't show the full wide screen. Switched back and the same problem persists.

If I unplug Monitor 1, Monitor 2 starts working (through the Anker hub). If I then plug Monitor 1 back in, Monitor 2 stops working. The background is the desktop pic instead of my error message.

Multiple restarts to no avail.

MacBook Air 15″, macOS 15.4

Posted on May 7, 2025 3:32 PM

Top-ranking reply

Lmstrs Author

Level 1

4 points

Posted on May 12, 2025 9:27 AM

I replaced the Anker mulitiport hub with the Apple branded one, and it works. The same "high speed" HDMI cable I was using works with the Apple hub. I replaced that cable with an ultra high speed cable (Anker), which also works.

I am going to replace the USBC-HDMI cable with a better one also to see if that helps my mouse not disappear when moving to different monitors. '

Thanks for the simple yet effective tip.

View in context

Macbook M4, 2nd monitor STOPPED working after a month

Similar questions