New 2024 MACBOOK M3 - not working with two screens in clamshell

Macs only support connecting two monitors to the same host port when that port is a Thunderbolt port, and the device immediately attached to it is a Thunderbolt device (like a Thunderbolt dock).

From the description of that adapter, it sounds like

• It is a plain USB-C adapter – not a Thunderbolt device
• They claim that it does not require additional software (implying that they're using native USB-C (DisplayPort) output, and not some "workaround" technology like DisplayLInk)
• They acknowledge that Macs do not support DisplayPort MST (for daisy-chaining of DisplayPort displays)
• They claim that you can use it to connect two monitors to a Mac in extended desktop mode

The last item does not square with the first three. It make me wonder if the description is accurate.

Here's a description of the NewMight HDMI Adapter for Dual Monitors on another Web store site. Definitely the same brand, quite possibly the same adapter.

https://www.neweggbusiness.com/product/product.aspx?item=9siv086k5u2948

This description also says that Macs do NOT support DisplayPort MST mode – and here the description draws the logical conclusion that you can't use this adapter to run two displays in extended display mode on a Mac - instead of providing an illustration of "extended display mode" on a Mac that seems to contradict all of the other text.

"Extend Mode: A-B/BB 

(Expanded 2 monitors with the same content ) 

It DOES NOT support extending 2 different screen on MacOS devices for the limitation of Mac itself. 

Extend Mode: A-B/BB/BC 

(Expanded 2 monitors with different content) 

Only Windows supports this Extend Mode (MST Function), MacOS DOES NOT support."

My guess is that if you want to have a single-cable connection to your Mac – instead of plugging each monitor into a different USB-C port – you would want to take a look at a Thunderbolt dock or hub from the likes of Other World Computing, SonnetTech, or CalDigit.