1. Quit any active applications that are using wi-fi or the internet (Safari, Chrome, etc)
  2. Turn OFF wi-fi by selecting the wi-fi menu bar item and choosing “Turn Wi-Fi Off”
  3. Open Finder in macOS and pull down the “Go” menu and choose “Go To Folder” (or hit Command+Shift+G to get there quickly)
  4. Enter the following path exactly into “Go to folder” window and choose “Go”

  5. /Library/Preferences/SystemConfiguration/

  6. Locate and select the following files in the SystemConfiguration folder

  7. com.apple.airport.preferences.plist
    com.apple.network.eapolclient.configuration.plist
    com.apple.wifi.message-tracer.plist
    NetworkInterfaces.plist
    preferences.plist
    fix macOS sierra wifi problems by trashing wireless preferences

  8. Remove those matching files, you can either place them into a folder on the desktop as a rudimentary backup, place them into the Trash without emptying, or actually delete them