Before you begin
- If you're using an AirPort Time Capsule or AirPort Base Station, make sure its firmware is up to date. If you're using a non-Apple router, check with the device's manufacturer for information on updating its firmware.
- If possible, back up or write down your current Wi-Fi settings before making changes. You can then put the original settings back if the steps you take don't appear to make a difference.
How to open Wireless Diagnostics
You can open Wi-Fi Diagnostics from the Wi-Fi menu. Try to connect to your Wi-Fi network, then use these steps to begin.
- Quit any other apps that are open.
- While pressing the Option key, click the Wi-Fi menu.
- Choose Open Wireless Diagnostics from the Wi-Fi menu.
- Enter an administrator name and password when prompted.
This opens the Wireless Diagnostics utility. Read the introduction in the window that appears, then click Continue. Wireless Diagnostics then tests the Wi-Fi connection to your base station or router, and checks your Wi-Fi configuration settings.
If no issues are found, Wireless Diagnostics lets you know that your Wi-Fi connection appears to be working. Click Continue to see the summary screen. If an issue is intermittent, you can select the option to monitor your Wi-Fi connection to diagnose your connection further.
At the Additional Information window you can enter a description of your Wi-Fi network or where your router is located. The information you include here is saved in a log file that's created when you finish Wireless Diagnostics.
Click Continue to see the Router Information screen. Enter the brand, model, and firmware version the Wi-Fi base station or router is using if you want to include this information in the log.
Click Continue to see a summary of what Wireless Diagnostics finds. The summary provides a list of any issues that were found and recommendations for fixing those issues. Click the info button next to an item to see more information.
For example, the following suggestions might be offered if your DNS settings appear to be configured incorrectly:
Follow the recommended steps for each item, then click Close when you're finished.
If you change your Wi-Fi settings as recommended by Wireless Diagnostics, but it doesn't fix your issue, try setting your Mac to forget or remove the previous Wi-Fi settings for your Wi-Fi network. Then join your Wi-Fi network again. This step prevents your Mac from trying to connect to your network using an older configuration.
Save a report
After finishing the assistant, a compressed file beginning with the name "WirelessDiagnostics-" is saved to your desktop. This file contains details about your wireless environment and your Wi-Fi connection. You can send this file to a network specialist (like your IT department or a consultant) if you still have issues connecting to your Wi-Fi network.
The following information is included in this file:
- com.apple.Bluetooth.plist files
- SystemConfiguration folder
- SystemDiagnosticReports folder
- UserDiagnosticReports folder
Monitor a Wi-Fi connection
Wireless Diagnostics also includes monitor mode. You can use this mode to help you diagnose intermittent issues like an unexpectedly dropped connection, or issues automatically connecting to a Wi-Fi network. When an issue is found, monitor mode automatically stops. It then collects information about what happened and presents a summary. Related information about the issue is saved to your desktop as part of a Wireless Diagnostics report.
To start monitor mode, open Wireless Diagnostics and proceed through the onscreen instructions. From the summary screen, select "Monitor my Wi-Fi connection" then click Continue.
When you monitor your Wi-Fi connection, a window with a progress bar appears to let you know that monitoring is in progress. You can continue to use your Mac, while monitoring happens, but you should leave the Wireless Diagnostics window open. If you close this window, monitoring stops.
Monitor mode continues to work when your Mac is on, and as your Mac sleeps and wakes. If you want to cancel monitoring, click either Continue or Start Over. Closing the window, selecting a different Wi-Fi network from the Wi-Fi menu, or restarting your Mac also stops the monitoring process.
If Wireless Diagnostics finds an issue, monitoring stops. You're given the option to continue monitoring, or to go directly to the summary screen.
Click Continue to see a summary screen with recommendations and to create a Wireless Diagnostics report on your desktop.
Wi-Fi best practices
Wi-Fi best practices are recommended configuration steps for most Wi-Fi routers. If you're having issues with dropped connections or automatically joining a network, click "Review Wi-Fi Best Practices" at the Wireless Diagnostics Summary screen for more help.
Generally, you should configure all Wi–Fi routers or base stations on the same network using similar settings. On dual-band Wi-Fi base stations, you must configure both bands to use the same network name to avoid issues with connectivity and reliability.
Wireless Diagnostics also includes built-in utilities for network specialists. Open Wireless Diagnostics, then choose a utility from the Window menu. In OS X Yosemite you can open more than one utility at a time.
Use this option to quickly view useful Wi-Fi and networking state information for your current connection.
This utility logs additional important information about the Wi-Fi interface, the wireless environment, and your Mac's current network configuration. The result is saved to a diagnostics report on your desktop. You should enable and disable background logging for specific logs when it's requested by your network specialist.
- Select the logs you want to capture from the list.
- Click the Collect Logs button.
- Define when to collect each type of log.
Wireless Diagnostics continues to collect logs even if you quit the app or restart the computer. Make sure you open Wireless Diagnostics again and deselect the options for logs after you are done collecting them.
Wi-Fi Scanning examines the Wi-Fi environment around you, and lets you know about nearby Wi-Fi routers. It includes information on the Network name, Password Security type, Protocol, Signal Strength and Noise, and the Channel, Band, and Country the router is designed for.
The Performance window shows information about your current connection and two live signal graphs.
The SNR graph compares the Signal and Noise transmission Ratio, where the Signal (dBm) graph separates the two. These numbers are relative, and there isn't an exact value that indicates an excellent signal relative to a poor signal simply because there are so many factors involved. Instead, an indicator showing the perceived quality of the Wi-Fi signal is displayed in the upper left.
- Poor - Unreliable wireless connection with frequent disconnects, poor throughput, and slow network performance
- Good - Reliable wireless connection with moderate throughout and network performance
- Excellent - Reliable wireless connection with excellent throughout and network performance
Bigger "Quality" numbers are better. As you move further away from your Wi-Fi router the numbers get smaller, and the signal degrades until you eventually lose your connection. This can also happen if there are physical materials blocking the signal between your Mac and the W-Fi router, such as walls containing bathroom tile, steel, etc.
Received Signal Strength Indication (RSSI) is better if the value (measured in dBm) is higher. For example, -45 is better than -55.
Noise is the opposite of signal. It's better to have less noise. For example, -90 is better than -80. The higher the Noise (blue line) rises, the poorer the signal quality.
The bigger the gap between RSSI and Noise, the better.
For example, if you're using a 2.4 GHz Wi-Fi network and is a microwave oven is turned on between the Wi-Fi router and the Mac, you might see the Noise line rise, and your Wi-Fi signal quality would not be as good.
Sniffer or Frame Capture
This utility lets you perform wireless packet captures for a network specialist. Use Sniffer if you want to collect a sample of Wi-Fi traffic for a reproducible issue.
- First select a channel. (The list of available channels varies by country.)
- Next, select the width.
- Click the Start button to begin the capture. The Sniffer utility then records the Wi-Fi traffic on the specified channel.
- Click Stop to end the capture.
- Once you stop the capture, a file ending in .wcap is saved to your desktop.
See Recommended settings for Wi-Fi routers and access points for recommended performance, security, and reliability settings.