When your Mac with macOS Sierra attempts to connect to a Wi-Fi network, it checks for issues that affect its ability to create a fast, stable, and secure connection. If your Mac detects an issue, the Wi-Fi status menu  in the menu bar shows a new item: Wi-Fi Recommendations. Choose it to see recommended solutions:

Analyze your wireless environment

Your Mac can use Wireless Diagnostics to perform additional analysis. 

1. Quit any apps that are open, and connect to your Wi-Fi network, if possible.
2. Hold down the Option key and choose Open Wireless Diagnostics from the Wi-Fi status menu .
3. Enter your administrator name and password when prompted.

Wireless Diagnostics begins analyzing your wireless environment:

If the issue is intermittent, you can choose to monitor your Wi-Fi connection:

When you’re ready to see recommendations, continue to the summary. Wireless Diagnostics asks for optional information about your base station or other router, so that it can include that in the report it saves to your Mac.

Having printing problems on your Mac?  Check out this article on how to fix it.

Click the info button next to each item in the summary to see details about that item. Wi-Fi best practices are tips that apply to most Wi-Fi networks.

Back up or make note of your network or router settings before changing them based on these recommendations—in case you need to use those settings again.

Monitor your Wi-Fi connection

Your Mac can monitor your Wi-Fi connection for intermittent issues, such as dropped connections. Follow the steps to analyze your wireless environment, but choose “Monitor my Wi-Fi connection” when prompted.

During monitoring, a window shows that monitoring is in progress. Monitoring continues as long as this window is open and you’re on the same Wi-Fi network, even when your Mac is asleep.

If Wireless Diagnostics finds an issue, it stops monitoring and shows a brief description of the issue. You can then resume monitoring or continue to the summary for details and recommendations.

Create a diagnostics report

Wireless Diagnostics automatically saves a diagnostics report before it displays its summary. You can create the same report at any time by holding down the Option key and choosing Create Diagnostics Report from the Wi-Fi status menu . It can take your Mac several minutes to create the report.

• macOS Sierra saves the report to the /var/tmp folder of your startup drive, then opens that folder for you.
  To open the folder manually, choose Go > Go to Folder from the Finder menu bar, then enter /var/tmp.
• OS X El Capitan or earlier saves the report to your desktop.

The report is a compressed file with a name that begins “WirelessDiagnostics.” It contains many files that describe your wireless environment in detail. A Tech Expert can examine them for further analysis.

Use other diagnostics utilities

Wireless Diagnostics includes additional utilities for network specialists. Open them from the Windows 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 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. 
  • 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 on your Mac.
• Monitor is similar to the Performance utility, but displays a smaller window that includes one graph showing signal (RSSI) and noise measurements over time, and another graph showing transmit rate over time.

Learn more

Additional recommendations for best Wi-Fi performance:

• Keep your router up to date. For AirPort Time Capsule, AirPort Extreme, or AirPort Express Base Station, check for the latest firmware using AirPort Utility. For non-Apple routers, check the manufacturer’s website. 
• Set up your router using Apple’s recommended settings, and make sure that all Wi–Fi routers on the same network use similar settings.
• If you’re using a dual-band Wi-Fi router, make sure that both bands use the same network name.