According to the official Wireshark System Requirements , was the final release branch to support OS X 10.11 El Capitan.
If the official DMG fails, many legacy users prefer MacPorts because it compiles software specifically for your system version, often maintaining better stability on older OSs like El Capitan than Homebrew. Command: sudo port install wireshark Does Wireshark work on Mac OS 10.11 El Capitan? wireshark download mac el capitan
Once complete, find Wireshark in your Applications folder and open it. Troubleshooting & Alternative Methods "Application not supported" According to the official Wireshark System Requirements ,