Resolving Wi-Fi Issues in macOS High Sierra

Fix Wi-Fi issues in macOS High Sierra



Some MacOS High Sierra users have reported issues with wireless networking after updating their Mac to the latest system software version. The problems may range from difficulties connecting to wi-fi networks, dropping wi-fi connections (particularly after waking from sleep), sluggish wireless speeds, and other frustrating connectivity problems with wi-fi networks.

This article will attempt to detail some common problems, and explain some troubleshooting steps to resolve wi-fi issues with macOS High Sierra.


Having Wi-Fi Problems in High Sierra? Update to the latest macOS High Sierra Update


Before doing anything else, if the Mac is currently on High Sierra then you should update to the latest version of macOS High Sierra that is available. Apple regularly releases software updates to system software, and macOS High Sierra is no different. If you are still running macOS High Sierra 10.13, then you need to update to the latest point release version available (10.13.1, 10.13.2, etc). This is easy, but you should always backup a Mac before installing any system software update.

  • Go to the  Apple menu and choose the App Store, then go to the “Updates” section and install any available system software updates to High Sierra

Point release updates often include bug fixes, and if you’re experiencing a problem that is related to a core system software bug then it’s possible the system software update will resolve that, possibly along with other reported problems

The bottom line: check for available system software updates and install them if any are available.


Is the Wi-Fi router SSID (name) hidden?


Some Mac users with MacOS High Sierra have reported difficulty connecting to wi-fi access points that have a hidden SSID.

You can try disconnecting and then connecting directly to the hidden SSID router in Mac OS, but the connection may drop again or fail upon waking from sleep.

One possible workaround is to make the SSID visible, this must be done on the wi-fi router itself and will vary per wireless access point, but if you have access to the wi-fi router it may be a solution. This works for many users, but obviously if you must have a hidden SSID for some reason then making the SSID visible is not always a viable option.


Does wi-fi only drop when macOS High Sierra wakes from sleep or screensaver wake?

Some users report that macOS High Sierra drops their wi-fi connection when waking from sleep or when waking from a screen saver, or that macOS High Sierra is slow to re-join wi-fi after waking from sleep.

You may be able to resolve wi-fi dropping after a Mac wakes from sleep by following the steps outlined below to create a new wireless configuration.

One reported workaround to wi-fi not re-joining after waking from sleep is the following:

  1. Go to the Wi-Fi menu and choose “Turn Off Wi-Fi”
  2. Wait a few seconds and then return to the wi-fi menu and choose “Turn Wi-Fi On”

Sometimes simply toggling the wireless capability off and on again is sufficient to resolve an inability to rejoin a wi-fi network. Some users are also reportedly turning off wi-fi before they sleep their Mac, and then enabling it again once their Mac is awake.

Another possible workaround is to use caffeinate at the command line, or an app like Caffeine or KeepingYouAwake, or sleep corner, to temporarily prevent sleep while those functions are activated. This is obviously not much of a solution if you must sleep a Mac.

Of course, workarounds are inconvenient and they are not true solutions. If you’re experiencing wifi connection problems then try the steps below to potentially resolve them.


Creating a New Wi-Fi Configuration in macOS High Sierra

Back up your Mac before continuing, these steps involve removing system level configuration files. Do not proceed without a backup made so that you can roll back if something goes wrong.

  • First, turn off wi-fi by pulling down the wi-fi menu bar item in the upper right corner and selecting “Turn Wi-Fi Off”
  • From the Finder, create a new folder onto the desktop (or another user folder) and call it something like “WiFiConfigBackup”
  • Go to Finder in macOS, and pull down the “Go” menu, then choose the “Go To Folder” option
  • Enter the following directory path into window and then click on “Go”


  • Find and select the following files that are located within the now open SystemConfiguration folder

  • Drag those files into the folder “WiFiConfigBackup” you created in the second step (alternatively, if you’re advanced, have a backup, and know what you’re doing, you can remove them)
  • Restart the Mac by going to the  Apple menu and choosing “Restart”, then let the Mac boot up as usual
  • Return to the Wi-Fi menu in the upper right corner and choose “Turn Wi-Fi On”, and then join the wireless network as usual

Essentially what this is doing is ditching your old wireless preferences and causing MacOS High Sierra to replace them by generating new wi-fi preferences. For many users, this is sufficient to solve any problems with wifi networking.


Optional: Make a New Custom Network Location

If you’re still having wi-fi problems after ditching the preferences and rebooting the Mac, you can try the steps below to create a new network location with custom configuration settings.

  • Go to the  Apple menu and choose “System Preferences”
  • Select the “Network” panel then choose “Wi-Fi” from the list
  • Near the top of the preference panel, pull down the “Location” menu and select “Edit Locations” from the dropdown

Create a new location in Network preferences

  • Click the [+] plus button to create a new network location, name it something like “FixWiFiCustomConfig” or whatever is easily identifiable to you, then click on “Done”

a new network location to resolve some wireless networking problems

  • Alongside Network Name, pull down the dropdown menu and select the wi-fi network to join, enter the password if applicable
  • Click on the “Advanced” button in the corner of the Network preference panel
  • Choose the “TCP/ IP” tab and click on “Renew DHCP Lease”

renew DHCP to get DHCP info filled in automatically

  • Next go to the “DNS” tab, and within the “DNS Servers” section click on the [+] plus button then add the following IP addresses (one entry per line, by the way these are Google DNS servers, you can use others if you’d prefer but these are particularly easy to remember and ubiquitous):

add custom DNS settings to improve DNS lookups

  • Next, select the “Hardware” tab and set the ‘Configure’ option to “Manually”
  • Adjust the “MTU” option to “Custom” and set the number to “1453”

The custom MTU setting in network preferences

  • Now click on “OK”
  • Finally, click on “Apply” to set the network changes you just made for the new network location
  • Exit out of System Preferences
  • Open Safari or Chrome, and visit a website – it should load fine

This sequence of trashing wi-fi preferences, generating new wireless preferences, and then, if need be, creating a new network location with custom DNS and MTU are a longstanding set of steps for resolving various wireless problems in many versions of Mac OS, including SierraEl Capitan, and before.


High Sierra Wi-Fi still not working?

If you’ve done all of the above and you’re still having issues with wireless networking, you can try some general troubleshooting tips too;

  • Try to connect to a completely different wi-fi network, if wi-fi works fine with other networks it could be an issue with the router
  • Connect a completely different device to the same wi-fi router, does it work fine?
  • Try adjusting the wi-fi router channel, or using 2.4GHZ instead of 5GHZ (or vice versa)
  • If all else fails and wi-fi worked fine before using High Sierra, you can downgrade macOS High Sierra to a prior version of macOS assuming you made a backup with Time Machine before updating to High Sierra. Downgrading is rather dramatic and should be considered a last resort