How to Troubleshoot & Fix MacOS Mojave Wi-Fi Issues

Nov 19, 2018 - 14 Comments

Troubleshooting wi-fi problems in macOS Mojave

Have you been experiencing wi-fi problems since installing MacOS Mojave 10.14 on a Mac? While MacOS Mojave works great for most Mac users with compatible Macs (and even for many Macs that are unofficially able to run Mojave), a small number of MacOS Mojave users have discovered that wireless networking is having difficulties for them. Typically the Mojave wi-fi issues are that the connection has either failed, drops frequently, won’t reliably connect to wi-fi, is unable to connect at all, or even that general wi-fi performance is suffering, and the symptoms appear to have arrived only after updating a Mac to macOS Mojave.

This troubleshooting guide will aim to troubleshoot and resolve wi-fi problems and issues with MacOS Mojave.

Troubleshooting Wi-Fi Problems with MacOS Mojave

We’ll walk through a variety of steps to troubleshoot wireless networking issues on the Mac. Some of these are fairly simple, while others are more complex and require setting up new network profile information, moving system files, using custom network configurations, and other techniques that typically resolve wireless.

Important: Back up the Mac before going any further. This is essential because some of the troubleshooting steps involves accessing and removing system level configuration files. A full system backup is essential so that you can restore from if something goes haywire, and to prevent data loss. Backing up a Mac with Time Machine is easy, don’t skip it.

Install Available Software Updates, & Reboot the Mac

It’s always a good idea to keep system software up to date, and thus your first step should be to check for any available system software updates and install them if applicable.

You can check for and install system software updates in macOS by going to the Software Update control panel in “System Preferences”. Be sure to backup your Mac before installing any system software update.

If you do not have any system software updates available, go ahead and restart the Mac anyway, as sometimes a simple reboot remedies wi-fi and network issues.

Disconnect USB 3 / USB-C Devices, Docks, Hubs, etc from the Mac

If your wi-fi works but is frequently dropping, unable to connect, operates extremely slow, or is nearly useless, a possibility exists of hardware interference with certain USB 3 or USB-C devices and the Mac. This is because some USB devices emit radio frequency that can interfere with wireless networking.

Yes this sounds strange, but apparently some users are discovering that certain USB 3 and USB-C docks, hubs, and adapters are interfering with their wi-fi performance, typically on the newer model MacBook and MacBook Pro computers, but it can impact other machines as well.

An easy way to check if this applies to you and your wi-fi issues is to disconnect any connected USB 3 or USB-C devices, docks, hubs, or adapters from the Mac.

If the wi-fi connection works fine with the USB device disconnected, then you have likely found the culprit for your wireless network issues. If the USB cable is long enough, you can try moving the USB device further away from the computer itself so that nearby interference is minimized.

Some users report that changing the network connection from 2.4ghz to 5ghz can fix this issue, or getting a higher quality shielded USB hub may make a difference too.

For what it’s worth, this same USB interference issue can impact Bluetooth performance as well.

Make a New Wi-Fi Configuration in MacOS Mojave

These steps will walk through removing existing wi-fi configuration files to create new ones, which often resolves network problems on a Mac. Here’s what you’ll need to do:

  1. Back up your Mac first if you have not done so already – do not skip making a backup
  2. Pull down the Wi-Fi menu bar item in the upper right corner of the screen and choose “Turn Wi-Fi Off” to temporarily disable wi-fi on the Mac
  3. Now go to the Finder, and in any easily accessible location (Desktop, Documents, etc), make a new folder named something obvious like “WiFi Backup Files”
  4. Next, pull down the “Go” menu in the Finder and choose “Go To Folder”
  5. Enter the following path in Go To Folder then select “Go”
  6. /Library/Preferences/SystemConfiguration/

  7. Locate and select the following files in the SystemConfiguration folder
  8. NetworkInterfaces.plist
    com.apple.wifi.message-tracer.plist
    com.apple.airport.preferences.plist
    preferences.plist

  9. Select those files and move them to the “WiFi Backup Files” folder you made a moment ago
  10. Now pull down the  Apple menu and choose “Restart”, this will restart the Mac
  11. After the Mac boots back up, click on the Wi-Fi menu in the upper right corner again, this time selecting “Turn Wi-Fi On”
  12. Join the wireless network as usual by finding the wi-fi access point in the Wi-Fi menu

Now try using the internet again as usual, by opening Safari and visiting your favorite website (which is osxdaily.com obviously!). Wireless networking should work fine for most Mac users at this point.

If you continue to have problems with wireless networking and wi-fi, proceed to the next troubleshooting method.

Create a New Network Location with Custom Settings

Detailed below is how to create a new network location using custom configuration settings for DNS and MTU, this can often resolve finicky network issues on the Mac (and other hardware for that matter).

  1. Quit out of any open app that uses the internet (Safari, Mail, Messages, Chrome, Firefox, etc)
  2. From the  Apple menu, choose “System Preferences”
  3. Choose the “Network” panel, then choose “Wi-Fi”
  4. Pull down the “Location” menu and select “Edit Locations” from the dropdown menu
  5. Create a new location in Network preferences

  6. Click the [+] plus button to create a new network location, give it an obvious name like “FixWiFi” then click on “Done”
  7. a new network location to resolve some wireless networking problems

  8. Pull down the dropdown menu next to “Network Name” and choose the wi-fi network to join, then enter the wi-fi password if necessary
  9. Now click on the “Advanced” button, seen in the corner of the ‘Network’ preference panel
  10. Click the “TCP/ IP” tab and now click on “Renew DHCP Lease”
  11. renew DHCP lease to get DHCP info filled in automatically

  12. Now select the “DNS” tab, and within the “DNS Servers” area click on the [+] plus button to add the following IP addresses as one entry per line:
  13. 8.8.8.8
    8.8.4.4

    (Note these IPs are Google DNS servers, but you can use CloudFlare DNS or OpenDNS or others if desired)
    adding custom DNS settings to improve DNS lookups on Mac

  14. Now choose the “Hardware” tab and set ‘Configure’ to “Manually”
  15. Adjust “MTU” to “Custom” and set the number to “1491”
  16. Choosing custom MTU settings in network preferences

  17. Click “OK” to accept the MTU changes
  18. Click “Apply” to set the network changes for the new network location
  19. Exit out of System Preferences
  20. Finally, open Safari, Firefox, or Chrome, and try to visit a website like http://osxdaily.com where it should load fine

This series of steps involving trashing wi-fi preferences to create new ones and using a new Network Location with defined DNS and MTU settings are some of the most consistent means of resolving software based wi-fi issues on the Mac. We’ve covered similar troubleshooting steps for wi-fi problems with other versions of Mac OS, including for High Sierra, Sierra, El Capitan, and many releases before, because it almost always works.

Reset the Wi-Fi Router / Modem

If you’re having problems with a particular wi-fi router and/or modem, try resetting the router and modem. Usually this just involves unplugging the router and modem for about 20 seconds, then plugging them back in again.

The exact process of resetting routers and modems can vary per manufacturer, and thus it would be impossible to cover all of the options here. If you’re not sure how to troubleshoot wi-fi network issues that are directly related to the wi-fi router and modem (cable, DSL, fiber, dial-up, etc), then contact your ISP for their technical support guidance.

Additional Wi-Fi Troubleshooting Steps

For what it’s worth, almost every single MacOS system software update seems to cause a small number of Mac users some wi-fi grief, and in most cases it’s just a matter of a corrupted plist file, a DHCP or DNS issue, or something fairly simple to resolve. This is no different with the MacOS Mojave 10.14 update (and even the 10.14.x updates), and so while the vast majority of Mac users will experience no difficulty with wireless networking and the software updates, some issues can crop up for small numbers of Macs. The good news is that it’s usually a simple resolution.

Did the above troubleshooting steps resolve your wi-fi problems in MacOS Mojave? Did you find another solution to your wireless networking issues? Share with us your thoughts, experiences with troubleshooting, and solutions for fixing wifi difficulties, by leaving a comment below!

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Posted by: Paul Horowitz in Mac OS X, Tips & Tricks, Troubleshooting

14 Comments

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  1. Roy says:

    Here’s another solution. Immediately after the Mojave installer was done I attempted a restart. Nope, hung. Force off, can’t fully boot. Force off again.

    This brought a huge smile to my face. No Mojave clean install. Back to El Capitan and eternal bliss.

    I stopped drinking Apple’s coolaid a long time ago.

  2. Deacon Blues says:

    Some additional helpful tips for fixing wi-fi problems in Mac OS Mojave

    – Set ipv6 to ‘manual’ (default is auto, turn it to manual) in Network settings

    – Disable Little Snitch (or update it can work, some versions were incompatible with Mojave)

    – Restart the router, restart the cable modem, restart the Mac

  3. vdiv says:

    Appreciate the effort and hope that people can solve their issues with WiFi using the provided by Paul instructions.

    It just bugs me that solutions to software problems these days employ a “shoot in the dark” and “sledge hammer” approaches with a substantial waste of time, collateral damage, and induced anxiety, rather than systematically finding the root cause and targeting that. Part of the problem is the near complete lack of transparency in the operation of the software. It is not clear at what stage things fail and why. This is only getting worse with an increase in the layers of complexity and abstraction.

  4. grumpyzebra says:

    Great reply vdiv. What ever happened to “it just works” and “plug and play”? This is the type of issue that we should ever have to endure. You almost have to be a programmer just to use WiFi…….please.

  5. Douglas says:

    This is all great but how do I get the Personal Hotspot option on the wi-fi menu to appear immediately or better still connect as the default. I get shown all the wi-fi networks available and have to wait a while before the Personal Hotspot section appears – then I can select it. – help??

    • vdiv says:

      You could try cleaning the list of saved Wi-Fi access points in macOS under Network Preferences, Advanced, Wi-Fi. Could also rearrange the list so your preferred Networks are at the top. Also make sure your iOS device is nearby and that Bluetooth on it and in macOS is on. That should speed up the display of your iOS hotspot device.

      To automatically connect (Instant Hotspot) you need both devices to be on the same iCloud account and to have Continuity/Handoff between the devices enabled:

      on macOS: System Preferences/General/Allow Handoff…
      on iOS: Settings/General/Handoff

      https://support.apple.com/guide/mac-help/hand-off-between-devices-mchl732d3c0a/mac

  6. Jim says:

    Great article. Do you have a similar one for iOs where I’m having similar problems? Many thanks!

  7. Gary Glenn Ross says:

    Great wi-fi troubleshooting step guide, this is about as thorough as you can get without being hand-held by a support rep I think…

    But I gotta say the USB-C thing is weird, knowing it is real. I just wonder why would Apple use a USB protocol that interferes with wi-fi and bluetooth, when they’re simultaneously removing all ports so we have to use wi-fi and bluetooth? Kind of weird, right?

    It’s so confusing that they have a huge page on their website trying to explain USB-C in general.

    https://support.apple.com/en-us/HT201163#16

    I’ll state the obvious for anyone who has tried to use it, but USB-C is a mess. Some things work, some don’t. Some charge, some won’t. Some are safe, some aren’t. Some interfere with some wireless bands, some don’t. CONFUSING!

  8. Old Coot says:

    Disconnect USB 3 / USB-C Devices, Docks, Hubs, etc from the Mac works for me on my MBP. Hopefully Apple recitifies this on future updates since High Sierra never had this problem.

  9. Miguel Taxa says:

    With 14.1.1 dont resolve.
    With 14.1.2 the issue continues?
    Thanks

  10. Dux says:

    I have WiFi issues since upgrading to High Sierra and then Mojave. At first, restarting solve this issue. Then tired of keep restarting my MBP, I tried to turn off WiFi connection then turn it back on. It works too. Then, suspicious that the culprit was Safari, I switch to Chrome. I never have WiFi issues then.
    I believe security feature in the Safari that shutting down the WiFi. Especially when you visit sites that deals with pop-up or malware like porn or software piracy.

  11. Civilized says:

    Hi
    Running Mojave 10.14.2

    removing the files in /Library/Preferences/SystemConfiguration/

    helped me with poor wifi performance. EXCELLENT!!!

    This happens more or less after every update to mojave for me

    (Mac Book Air 2015 ish version)

    Br Civ

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