Mac OS Network Troubleshooting Guide


Overview

This article contains instructions for self-troubleshooting network connectivity issues on MacOS devices when using UCSD's supported networks (ie UCSD-PROTECTED, UCSD-GUEST, RESNET-PROTECTED, RESNET-GUEST). Following the steps will reset wireless configurations and settings, and typically will fix most connectivity issues on Mac devices.
 

Critical Concepts

Steps to Take

Basic Troubleshooting Steps to Do Beforehand:

  1. Note your network speeds (download and upload) prior to troubleshooting by either searching on Google "speed test" or using a site such as speedtest.net or fast.com. Download speeds below 20mbps are not ideal. Run another test after troubleshooting to see if a significant change has been made.
  2. Note your current operating system version by clicking the Apple icon  on the top left and selecting "System Preferences". It will say the device's macOS release version (macOS Ventura, Monterey, Big Sur, Catalina, etc.) and the version number (Version 12.3.1, etc.). If possible, please update to the latest version by clicking System Preferences > Software Update.
  3. Get your public IP address by going on a site such as whatismyipaddress.com, and confirm you are not border blocked using our site amiblocked.ucsd.edu. If you are blocked, contact us using the methods above and make sure to provide your IP address when communicating with the tech.

 

1. Verify Network Configuration

  1. On the top right, click the Wi-Fi icon and select "Network Preferences..." (macOS <13) or "Wi-Fi Settings..." (macOS 13).
    macOS (macOS <13)
    macOS Ventura (macOS 13)

  2. On macOS 13, you will need to click the "Network" item in the left sidebar. Otherwise, stay on this page.
  3. On macOS 13, check under "Other Services" or click on "VPN & Filters" to find the interfaces. On macOS <13, look at the left sidebar and see what interfaces are shown. Any VPNs or anything that is not recognized should be removed with the minus sign located on the bottom left, and by uninstalling the corresponding application by going to the Applications folder and dragging it into the Trash.
    macOS (macOS <13)
    macOS Ventura (macOS 13)

  4. Click on "Advanced..." on the bottom right.
    1. On MacOS Ventura, select "Wi-Fi" first and then "Details..."
  5. Click on the "TCP/IP" option.
    1. Ensure "Configure IPv4" is set to "Using DHCP", "Configure IPv6" is set to "Automatically"
    2. Click on the button "Renew DHCP"
      macOS (macOS <13)macOS Ventura (macOS 13)

  6. Click on the "Proxies" option and ensure all protocols are unchecked.
    macOS (macOS <13)macOS Ventura (macOS 13)

  7. Click "OK", click "Apply" on the bottom right, and then close it.

 

2. Forget Networks

  1. On the top right, click the Wi-Fi icon and select "Network Preferences..." (macOS <13) or "Wi-Fi Settings..." (macOS 13).
  2. Look in "Preferred Networks" and delete any UCSD networks (e.g. UCSD-PROTECTED, UCSD-GUEST, RESNET-PROTECTED, RESNET-GUEST-DEVICE) by clicking on them, then clicking the minus (-) icon, and then restarting the device (important to ensure that they are fully deleted). RESNET-GUEST-DEVICE and UCSD-GUEST can cause issues in particular when they are remembered at the same time as RESNET-PROTECTED and UCSD-PROTECTED, so it is strongly suggested to only connect to the PROTECTED networks.
  3. Having too many WiFi network profiles can cause issues connecting to campus Wi-Fi (and the VPN). Forget networks you aren't using - ideally getting down to 3-5 networks.
  4. Click "OK" or "Done"
    macOS (macOS <13)
    macOS Ventura (macOS 13)

  5. Check if you are able to connect to any of our networks now

 

3. Flush DNS

  1. Flushing your DNS cache will remove your local DNS records and stored IP addresses. Clearing your DNS cache is perfectly safe and can solve your connection issue.
  2. Open the Terminal
  3. Enter the command: 
    sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder

 

4. Delete Certificates

  1. Open the Keychain Access application by searching for "Keychain Access" on either the top right search icon or with command (⌘) + space bar
  2. Ensure the side bar is set to "login" and the tabs at the top is set to "Certificates"
  3. If there is more than 1 certificate named "auth.ucsd.edu," or any other certificates with a name involving UCSD such as "UC San Diego Certificate Service", delete all of them by holding down control (^) while clicking on them, and selecting "Delete"
    • There should be only ONE auth.ucsd.edu certificate; if this isn't correct, delete all certificates, so the device can request a new SSL certificate 
    • Note the times they expire as well
  4. Restart the device
  5. Click on the Wi-Fi symbol on the top right and connect to a UCSD network
  6. It should prompt you to authenticate with a certificate. Select "Show Certificate"
  7. Click on "Trust" and ensure all the settings are set to "Always Trust"
  8.  Click "Continue" and see if you are experiencing any issues connecting

 

5. Disable IPv6

  1. Disable IPv6 by typing the following command into Terminal: 
    networksetup -setv6off “Wi-Fi”

 

6. Delete PLists

  1. As a warning, deleting the following PList files will clear all saved network preferences and configurations 
  2. Open the "Finder" application
  3. Click on "Go" on the top menu bar, select "Go to Folder," and type "/Library/Preferences/SystemConfiguration"
    • Delete the following files by dragging them to the Trash: 
      1. CaptiveNetworkSupport, com.apple.network.eapolclient.configuration, com.apple.airport.preferences.plist, preferences.plist, NetworkInterfaces.plist
  4. Restart your Mac device

 

7. Make MacOS roam to strongest Wi-Fi signal

  1. Open the Terminal application by searching for "Terminal" with either the top right search icon or with command (⌘) + space bar
  2. Type in the following command:  
    sudo /System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport prefs joinMode=Strongest
  3. Press enter. You will need to enter your system password and press enter again for the change to take effect. It might not look like you are typing anything because your password is hidden.
  4. Restart your computer.

 

8. Uninstall and Reinstall Cisco's AnyConnect VPN Client (for M1/M2 MacBooks only)

  1. If you already have the Cisco AnyConnect VPN client installed and are using an M1 or M2 MacBook (click Apple icon , Chip will be Apple M1 or M2), uninstall it to see if the WiFi issue is resolved:
    • Open Finder application, open "Applications" folder, open "Cisco" folder, and run "Uninstall AnyConnect" application
  2. Check if you are able to successfully connect to our networks and maintain a stable connection
  3. Reinstall the "Cisco Secure Client" from the App Store using this link: Cisco Secure Client
    • Note, this installation only works for M1/M2 MacBooks

 

9. Turn off AWDL Interface (for M1/M2 MacBooks only)

  1. If you are experiencing connectivity issues on your M1 or M2 MacBook specifically (Click Apple icon , Chip will be Apple M1 or M2), this may be caused by the AWDL interface (a Wi-Fi mesh peer-to-peer network used in AirDrop and AirPlay). For more information, see the following articles by Meter and UCLA respectively: Recent Apple updates leading to WiFi issues & an interim solution, Intermittent Connectivity for Wireless Networks. To resolve this, there are a few steps you may take:
    1. Update the MacBook to macOS Ventura 13.1. Wi-Fi issues are supposedly resolved in this version.
      1. Open "System Settings" or "System Preferences" > General > Software Update
      2. If there are any updates available, please update the device.
  2. If you are unable to update their device, there are some interim steps you may take that might resolve the issue.
    1. Open Finder. Click Go > AirDrop from the drop down menu. At the bottom of the window, click where it says, "Allow me to be discovered by:" and select "No One" from the drop-down menu.

 

If you still have questions or need additional assistance, submit a ticket or call the ITS Service Desk at (858) 246-4357