MacBook Pro M4 only connecting to one external monitor

Issue :

I'm not able to connect to my 2 external monitors


Laptop : Macbook Pro M4 ( Sequoia )

Monitor : Dell U2421E x2


I'm using a separate Dell USB C cable for both monitors. 1 cable for 1 Thunderbolt port.

I'm able to connect both yesterday, but today, looks like it only allow 1 monitor at a time.

Posted on Nov 17, 2025 11:25 AM

Reply
2 replies

Nov 17, 2025 12:15 PM in response to Mrye92

that dell U2412E display appears to eb a 1920 by 1080 8 bits/color display up to 83 Hz refresh rate

Interfaces

  • DisplayPort (DisplayPort 1.4 mode)
  • HDMI (HDCP 1.4)
  • USB-C 3.2 Gen 1 upstream/DisplayPort 1.4 (power up to 90W)


one display on each of two USB-C cables should work for up to two external displays on MacBook Pro M4 plain or PRO models


PROVIDED those USB-C cables are no longer than ONE meter, maximum.

MacBook Pro M4 only connecting to one external monitor

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