Fix Slow Wi-Fi on Mac OS X by Reset Wi-Fi configuration and Advanced Wireless Troubleshooting

Fix Slow Wi-Fi on Mac OS X by Reset Wi-Fi configuration and Advanced Wireless Troubleshooting. After use Mac OS X for a long time or OS upgrade, the signal indicate the wifi connection is in good state, however the Wifi connection speed became very slow, with speed test result less than 1MB/s in very good router signal coverage.

September 16, 2021

Slow Wi-Fi Symptom

After use Mac OS X for a long time or OS upgrade, the signal indicate the wifi connection is in good state, however the Wifi connection speed became very slow, with speed test result less than 1MB/s in very good router signal coverage.

Fix Slow Wi-Fi Solution

The easiest way to solve this issue is reset system wifi configuration.

First turn off wifi by selecting the wi-fi menu bar item and choosing Turn Wi-Fi Off

Then open a terminal and run following commands to move the exist wifi related configurations to a backup folder:

mkdir -p ~/SystemConfiguration.bak
cd /Library/Preferences/SystemConfiguration/
sudo mv -f com.apple.airport.preferences.plist ~/SystemConfiguration.bak/
sudo mv -f com.apple.network.eapolclient.configuration.plist ~/SystemConfiguration.bak/
sudo mv -f com.apple.wifi.message-tracer.plist ~/SystemConfiguration.bak/
sudo mv -f NetworkInterfaces.plist ~/SystemConfiguration.bak/
sudo mv -f preferences.plist ~/SystemConfiguration.bak/

Note

If you do not want to backup old configurations, you can delete (replace command mv with rm) them.

Then restart Mac. Go back to the Wi-Fi menu and choose Turn Wi-Fi On. Mac OS X will use default wifi configuration and wifi speed should back to normal.

Advanced Wireless Diagnostics Troubleshooting

Wireless Diagnostics includes additional utilities for network specialists. Open them from the Window menu in the Wireless Diagnostics menu bar:

Info gathers key details about your current network connections.
Logs enables background logging for Wi-Fi and other system components. The result is saved to a .log file in the diagnostics report location on your Mac. Logging continues even when you quit the app or restart your Mac, so remember to disable logging when you’re done.
Scan finds Wi-Fi routers in your environment and gathers key details about them.
Performance uses live graphs to show the performance of your Wi-Fi connection:
- Rate shows the transmit rate over time in megabits per second.
- Quality shows the signal-to-noise ratio over time. When the quality is too low, your device disconnects from the Wi-Fi router. Factors that affect quality include the distance between your device and the router, and objects such as walls that impede the signal from your router. Learn more.
- Signal shows both signal (RSSI) and noise measurements over time. You want RSSI to be high and noise to be low, so the bigger the gap between RSSI and noise, the better.
Sniffer captures traffic on your Wi-Fi connection, which can be useful when diagnosing a reproducible issue. Select a channel and width, then click Start to begin capturing traffic on that channel. When you click Stop, a .wcap file is saved to the diagnostics report location (/var/tmp) on your Mac.

References

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