This monitor is compatible with a MacBook Air, but you need to use the right cables and settings to display the image correctly. This model has a DisplayPort input and an HDMI input. For a recent MacBook Air, we recommend using a USB-C to DisplayPort or USB-C to HDMI cable, depending on the ports available on your MacBook Air. If you only get the wallpaper, it's possible that the MacBook is detecting the monitor as a secondary screen in extended desktop mode with no windows open on it, or that the resolution or refresh rate are not properly configured. In the macOS system preferences, in the Monitors section, make sure that the monitor is correctly detected and configured in QHD resolution (2560 x 1440) and at 60 Hz, which is the monitor's native frequency. Bottom line: - Use a USB-C to DisplayPort or USB-C to HDMI cable to connect the MacBook Air to the monitor. - Check in macOS that the monitor is correctly detected and configured for 2560 x 1440 pixel resolution and 60 Hz. - If necessary, try disconnecting and reconnecting the cable, or changing the port on the MacBook. This Dell P2723D monitor works with macOS, but it doesn't have specific Mac support advertised, so some manual adjustments may be necessary.

No, connecting two monitors via DisplayPort (at least 1.2) cannot be done with this monitor, it does not support MST (Multi Stream Transport) protocol. The P2723DE model could, but it's a little more expensive: Dell P2723DE (2560 x 1440 Pixels, 27 ")