That usually means a problem with the Internet connection. When you startup the computer you should be asked to choose an Internet connection from a list of available networks. You choose the one that you use, enter the password for the connection, then click on an OK button or checkbox. Here is the installation procedure:
Internet/Network Recovery of El Capitan or Later on a Clean Disk
If possible, back up your files before proceeding.
- Restart the computer. Immediately, at or before the chime, hold down the (Command-Option-R) keys until a globe appears.
- The Utility Menu will appear in from 5-20 minutes. Be patient.
- Select Disk Utility and click on the Continue button.
- When Disk Utility loads select the target drive (out-dented entry w/type and size) from the side list.
- Click on the Erase button in Disk Utility's toolbar. A panel will drop down.
- Set the partition scheme to GUID.
- Set the Format type to APFS (SSDs, only if installing Mojave or Catalina ) or Mac OS Extended, (Journaled.)
- Provide a volume name, usually "Macintosh HD."
- Click on the Apply button, then click on the Done button when it activates.
- Quit Disk Utility and return to the Utility Menu.
- Select Install OS X and click on the Continue button.
This should install the version last installed on the computer or the latest version of macOS.
