Note: a portable Mac will not wake unless connected to a power source. Click here for more details.
Check the Mac's Energy Saver settings
- On the Mac you wish to connect to, open System Preferences.
- Click Energy Saver.
- Click Power Adapter (if present).
- Ensure that Wake for Wi-Fi network access and/or Wake for network access is enabled.
- Click the Apple menu in the system menu bar.
- Click Sleep.
Turn your attention to Screens and attempt to connect to the Mac. If the Mac doesn’t wake, and Put hard disks to sleep when possible was enabled for this connection attempt, go back and disable this feature, then try connecting again.
If the Mac doesn't wake and the connection fails:
- Open System Preferences.
- Click Energy Saver.
- Enable Prevent computer from sleeping automatically when the display is off.
Try connecting again. If the Mac still doesn't wake, consider the following...
Connecting to a MacBook? Is it plugged into a power source?
If you are connecting to a MacBook, MacBook Air, MacBook Pro or any other Apple laptop, it needs to be plugged into a power source (power outlet, external display with power, etc.) or it will not be able to wake up.
When plugged into a power source, your Apple laptop can be in clamshell mode and it will still respond to connection requests.
Is the Mac's system volume encrypted with FileVault?
Your Mac's FileVault feature could be interfering, especially if you find that a user must physically log into the Mac before Screens can connect:
“To ensure security when you turn on FileVault, other security features are also turned on. For example, when you turn on FileVault, you need a password to log in when your Mac is in sleep, or after leaving the screen saver.”
There are a couple of work-arounds available to you:
- Disable FileVault
- Restart the remote Mac with the following Terminal command to bypass the start-up authentication required by FileVault: sudo fdesetup authrestart
- Disable the screen saver or the password requirement:
It is also a known issue that ARD may cause connection issues in some circumstances. The solution for this is to re-install ARD, as mentioned in this thread:
The latest of Remote Desktop is available here.