External monitor help.

[krspkbl]

I got a new monitor recently and hoped to use my M3 Air with it.

With the laptop open it works just fine. Monitor gets a signal and the monitor KVM works so I can use my external keyboard and mouse.

When I close the lid it loses signal. I bought a vertical stand for the Air thinking I could sit it in that while connected to the monitor.

Do I really need to keep it open to use it?

I’m using a Thunderbolt 4 cable and my monitor has 90W power which charges the laptop.

What am I doing wrong or is this normal?

 

[Juicy Box]

I am not sure if something has changed with AS, but all my Intel Mac laptops work in clamshell mode, but you have to have an external display, keyboard, mouse connected, and connected to power for it to work.

That said, it looks like many people have had issues with this on Sonoma, Ventura, and Monterey. Not too many older results with searching, so not sure what has happened with recent MacOS updates breaking this for some people.

There are two results with potential solutions that I found pretty quickly:
https://www.reddit.com/r/MacOS/comments/16zqw03

Clamshell mode does not work - Apple Community

discussions.apple.com

There are a few suggestions/workarounds in both links, so try them and see if they correct your issue.

 

[krspkbl]

I got it working. I downloaded Amphetamine app which lets me use just the thunderbolt cable. Everything is good now.