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Question: Wi-Fi and Hard-Wired Ethernet connection no longer works after High Sierra upgrade

I have a new MacBook Pro and recently updated macOS to High Sierra (10.13.3). However, since that time I have been unable to access the Internet via either WiFi or hardwired Ethernet connection (via Thunderbolt to USB+cable adapter). Internet to all other devices in my house (including both hardwired and WiFi) work just fine. Only the new MacBook Pro cannot connect to the Internet.


Let me know if there is anything I can do to remedy.

Thanks, Rob

MacBook Pro with Retina display, macOS High Sierra (10.13.3)

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Feb 28, 2018 10:49 AM in response to Robert Wald In response to Robert Wald

A Troubleshooting Protocol to Identify Problems or Fix macOS El Capitan or Later

You should try each, one at a time, then test to see if the problem is fixed before going on to the next.


Be sure to backup your files before proceeding if possible.


  1. Shutdown the computer, wait 30 seconds, restart the computer.
  2. Disconnect all third-party peripherals and remove any support software like drivers and plug-ins.
  3. Resetting your Mac’s PRAM and NVRAM
  4. Reset the System Management Controller (SMC)
  5. Start the computer in Safe Mode, then restart normally. This is slower than a standard startup.
  6. Repair the disk by booting from the Recovery HD. Immediately after the chime hold down the Command and R keys until the Utility Menu appears. Choose Disk Utility and click on the Continue button. Select the indented (usually, Macintosh HD) volume entry from the side list. Click on the First Aid button in the toolbar. Wait for the Done button to appear. Quit Disk Utility and return to the Utility Menu. Restart the computer from the Apple Menu.
  7. Create a New User Account Open Users & Groups preferences. Click on the lock icon and enter your Admin password when prompted. On the left under Current User click on the Add [+] button under Login Options. Setup a new Admin user account. Upon completion log out of your current account then log into the new account. If your problems cease, then consider switching to the new account and transferring your files to it - Transferring files from one User Account to another.
  8. Download and install the OS X El Capitan 10.11.6 Combo Update or 10.12.6 Combo Update or Download macOS High Sierra 10.13.3 Combo Update as needed.
  9. Reinstall OS X by booting from the Recovery HD using the Command and R keys. When the Utility Menu appears select Reinstall OS X then click on the Continue button.
  10. Erase and Install OS X Restart the computer. Immediately after the chime hold down the Command and R keys until the Apple logo appears. When the Utility Menu appears:
  1. Select Disk Utility from the Utility Menu and click on Continue button.
  2. When Disk Utility loads select the drive (out-dented entry) from the Device list.
  3. Click on the Erase icon in Disk Utility's toolbar. A panel will drop down.
  4. Set the Format type to APFS (for SSDs only) or Mac OS Extended (Journaled.)
  5. Click on the Apply button, then wait for the Done button to activate and click on it.
  6. Quit Disk Utility and return to the Utility Menu.
  7. Select Reinstall OS X and click on the Continue button.

Feb 28, 2018 10:49 AM

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Feb 28, 2018 11:29 AM in response to Robert Wald In response to Robert Wald

Thanks for your input but I am loathe to proceed with all but step #1 (which did not work) because this is a brand new Mac. I will just take it back to the Apple Store as it is still covered by Apple Care. It should also be noted that both WiFi and Ethernet connection were working just fine until the OS upgrade.

Feb 28, 2018 11:29 AM

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Feb 28, 2018 11:33 AM in response to Robert Wald In response to Robert Wald

Hence, the above process. Not sure why you would be loathe to try each step to see if it fixes the problem. At least work your way through Step 7. If it still doesn't work and you won't reinstall macOS, then make an appointment at the Apple Genius Bar for service. If you need to find an Apple Store - Find a Store - Apple.

Feb 28, 2018 11:33 AM

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Mar 1, 2018 2:05 AM in response to Robert Wald In response to Robert Wald

Have you tried restarting your router? Or, checking if your Wi-Fi is showing a repetitive pattern of Wi-Fi on, then searching? Have you tried a different network?

If you've not run Wireless Diagnostics, I highly advise to do so.

Mar 1, 2018 2:05 AM

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Question: Wi-Fi and Hard-Wired Ethernet connection no longer works after High Sierra upgrade