Q: macbook air rebooting on wakeup from sleep when connected to external monitor

Hey farazfastian,

I see that you are experiencing some issues with your MacBook Air when connected to an external monitor. I have an article for you with some helpful troubleshooting steps that can be beneficial when addressing this issue:

Get help with video issues on external displays connected to your Mac - Apple Support

https://support.apple.com/en-us/HT201177

Thanks for coming to the Apple Support Communities!

Hey again farazfastian ,

If you can get to an Apple Retail Store easily, then taking the computer to the Genius Bar is definitely a good option. Some further steps you can do on your own to address this issue before you go to the Genius Bar can be found here:

If the previous steps don't work

These additional steps may help identify or resolve the issue: 

• Reset the SMC.
• Reset NVRAM.
• Disconnect external devices other than your Apple keyboard, mouse, and display. If that resolves the issue, gradually reconnect your devices, testing each time, until you find the device that is interfering with sleep. Then check the documentation that came with the device, or contact the device manufacturer.
• Start up in Safe Mode to see if the issue is related to non-Apple startup items, login items, or kernel extensions. 
• Try to isolate the issue by using another user account. 

If your Mac doesn't sleep or wake when expected - Apple Support

https://support.apple.com/en-us/HT204760

Thanks for coming to the Apple Support Communities!

If you are still concerned about your MacBook Pro and feel like the issue is not yet fully resolved, you may wish to take the computer to the Genius Bar if that is convenient for you. You may find more information by using another one of Apple's support resources - https://getsupport.apple.com/GetproductgroupList.action.
 
Thanks for being a part of the Apple Support Communities!