If you see this message when trying to connect from VNC Viewer, check the following in order:
- If you have a Home or Professional subscription, check that the remote computer is connected to the Internet. If it isn't, you won't be able to connect. The same applies if you have an Enterprise subscription and are establishing a cloud connection.
- It may be that the remote computer is asleep. It is advisable to prevent a remote computer sleeping or hibernating while remote access is required:
- Windows: In Control Panel > Power Options > Change when the computer sleeps, make sure Put the computer to sleep when plugged in is Never.
- Mac: In System Preferences > Energy Saver, make sure Prevent computer from sleeping automatically when the display is off is selected.
- If you have changed your RealVNC account credentials (email address and/or password) recently, you will need to sign out from VNC Viewer (File > Remove account) and then sign back in again. You might want to check Remember passwords for next time I sign in if you have saved passwords for connections.
If you still have problems, please enable debug logging on both VNC Server and Viewer, try making a new connection, and send over both vncserver.log and vncviewer.log. See https://www.realvnc.com/docs/logging.html for more information.