Use Wireless Diagnostics
Wireless Diagnostics analyzes the Wi-Fi network your Mac is connected to, and provides solutions to help resolve wireless connectivity issues.
If you can connect to your Wi-Fi router, but have issues loading webpages, sending or receiving email, or streaming music or video, use Wireless Diagnostics to analyze the network’s connection to the Internet. After the analysis is complete, you get a list of issues and possible solutions.
Wireless Diagnostics collects detailed logs you can provide to a network specialist, network administrator, or an IT support person.
Wireless Diagnostics also generates a compressed file containing details found during the diagnosis, which is saved to /var/tmp. The file’s name starts with WirelessDiagnostics- and ends with .tar.gz. This file may be useful to your network administrator, service provider, or IT support person.
Note: Wireless Diagnostics doesn’t change your network settings.
Quit all open apps.
Try to join the Wi-Fi network you’re having problems with (if you are not already connected).
Press and hold the Option key, click the Wi-Fi status icon
in the menu bar, then choose Open Wireless Diagnostics.Follow the onscreen instructions to analyze your network connection.
For more information, see the Apple Support article Use Wireless Diagnostics to help you resolve Wi-Fi issues on your Mac.