Belkin Thunderbolt 4 5-1

Are you closing the lid of the MacBook Air?

The M3 MacBook Air only supports two external displays when the lid is closed. When the lid is open, it needs one of the video outputs from the M3 chip to drive the built-in screen.

Use dual monitors with your MacBook Air and MacBook Pro with M3 chip - Apple Support

RuiLo24 wrote:

I buy the Bellini Thunderbolt 4 with 3 usb-c thunderbolt exit for connecting 3 screens, without that I now the Mac can connect only with 2 when the lid is close.

I pay to apple 240€ for that and I can’t use.

Please give one solution

Your Mac does not support three external displays. It only supports two external displays – and then, only when the lid is closed. This information was readily available in the Technical Specifications that Apple made available before you bought your Mac.

MacBook Air (15-inch, M3, 2024) - Technical Specifications - Apple Support

If you wanted a Mac notebook that supported three external displays, you should have bought a 14" or 16" MBP that had a M3 Max chip.

MacBook Pro (14-inch, M3 Pro or M3 Max, Nov 2023) - Technical Specifications - Apple Support

MacBook Pro (16-inch, Nov 2023) - Technical Specifications - Apple Support

I am not familiar with your particular Thunderbolt 4 dock. I know that some Thunderbolt docks and hubs are able to split a single Thunderbolt chain into three Thunderbolt chains. That does not mean that you can hook displays to all three downstream Thunderbolt ports. Typically what a Thunderbolt dock allows you to do is to connect two monitors to a Mac that supports multiple external displays. (The reason there are three downstream ports is that displays are not the only thing that people use docks to connect.)

RuiLo24 wrote:

But in several videos the people use the belkin or another software for to have more screen with lid open

Your Mac does not support having two external displays with the lid open – let alone three! You are lucky that it is a M3 MacBook Air – not a M1 or M2 model. On those models, the limit was one external display, period - whether the lid was open or shut. The M1 or M2's other video output was permanently dedicated to the built-in screen.

There is no dock or software that can add more first-class, hardware-supported video outputs. What you saw on those videos was either

• People with more capable hardware, using it in supported configurations, or
• People using second-class "workarounds" that can come with significant compromises

Although it can be useful to read third-party reviews or watch third-party videos, when you are buying a computer, it is a really bad idea to rely on those as a substitute for reading the Technical Specifications of the computers that you are considering.