How to VNC connect to a sleeping iMac?

Question

I use RealVNC to connect to an intel-based iMac, but it cannot wake it up if it is asleep after long inactivity. Yes, I don't change the setting to prevent from sleeping but only leave 'Wake for network access' on. However, the same works perfectly to connect a sleeping Mac Studio. This obviously has the merit of letting the machine rest and saving energy.

Both 'server' machines use WiFi and the other machine used to control them is not necessarily within the same local network. The 'server' machines do not have a public IP addresses. I tried to compare the settings like in 'Energy Saver' between the two host machines, but still have no clue.

When testing this, I noticed that I still can connect to the iMac right after (like 10 seconds) I manually put it to sleep. If I wait a few minutes, it does not work.

Answer 1

The Screen Sharing application included with macOS should be able to wake a sleeping Mac. Apple does provide instructions at the website Share the screen of another Mac. Below is an example of where I use screen sharing without needing an user to give permission at the remote server Mac. Here, I assume screen sharing is enabled on the server.

	Client	Server
Mac	2011 iMac	2018 Mac mini
macOS	High Sierra	Mojave

The steps are given below.

1. Start by right clicking on the Finder icon on the dock and selecting "Connect to Server...", as shown below.

   

2. In the "Connect to Server" popup, enter the server ip address (or name.domain) preceeded by vnc://, as shown below. Next, select the Connect button.

3. You should get a popup similar to the one shown below.

   

4. When the popup shown below appears, enter a username and password of an account on the server, as shown below. Next, select the Connect button.

   

5. You should get a popup similar to the one shown below.

   

6. Choose the radio button which begins with "Log in as yourself:". Next, select the Connect button.

   

7. You should get a popup similar to the one shown below.

   

8. The following log in screen appeared. Since I know Ron Janzen is currently logged in at the server Mac, I can screen share by selecting this user.

   

9. After selecting Ron Janzen, I am prompted for Ron Janzen's password, as shown below.

   

After entering Ron Janzen's password, I am allowed to screen share. For privacy purposes, an image has been omitted.

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Remote Log In without Screen Sharing

In step 8 above, I could have selected an user which is not logged in. Doing so would allow me to access a remote desktop without interfering with the current user logged in at the server Mac. For example, if I selected David Anderson in step 8 above, then the password for David Anderson's account on the server would be asked for, as shown below.

After entering the password, the window shown below appeared.

Note: the server Mac has two displays. After selecting to only view the first display and selecting scaling, the following window is shown.