Can't display 2 monitor on my MacBook Air M3

Do you have the MBA closed when connecting to the dock? The MBA does not support two external displays unless it is closed:

Use an external display with your MacBook Air - Apple Support

MacBook Air (13-inch, M3, 2024) - Tech Specs - Apple Support

rsmartinez wrote:

Hello,

I am using a HP USB-C Dock G5 and when I connect to my laptop it does display my second monitor. It only mirrors my first monitor and not extend it. Ive tried with using Display port and HDMI cables to see if that would work but nothing happens. How can this be resolved ? or What is the issue?

I believe that one issue is that it is a plain USB-C dock – not a Thunderbolt dock.

Macs do not support DisplayPort MST daisy-chaining or its equivalent in the way that Windows PCs do. They will only send out two video signals over one port if that port is a Thunderbolt port, and the device that is immediately connected to it is a Thunderbolt device.

HP's description says "Designed with universal compatibility in mind, this dock works with both HP and non-HP USB-C®- and Thunderbolt™-enabled laptops." But I don't think it actually uses Thunderbolt. I think it probably relies on DisplayPort Alt Mode, USB 3, and the equivalent of DisplayPort MST daisy-chaining.

From a Mac's point of view, there is only ONE video signal feeding the three video ports (two DisplayPorts and a HDMI port) on the dock. This is why you can only mirror displays. The Mac might not even know that you have multiple monitors attached.

The following support article seems to suggest that you may need to connect both monitors directly to the laptop to actually support two monitors as extended and not mirrored if it's not working with your dock: Use dual monitors with your MacBook Air and MacBook Pro with M3 chip - Apple Support

Someone with more experience may be able to provide additional suggestions but as it may be that your particular dock isn't currently able to support this with its current firmware.

Sorry -- "MacBook Air" (MBA)