It seems that the Endpoint Security VPN (I have the Checkpoint client but the Symantec is also culpable) mingles around and blocks any incoming connections and any PING echo requests.
So the solution is to kill the agent:
Copy to clipboard sudo launchctl unload /Library/LaunchDaemons/com.checkpoint.epc.service.plist sudo kextunload /Library/Extensions/cpfw.kext and turn the AutoLaunch off by setting the RunAtLoad and KeepAlive PLIST values to false:
Copy to clipboard sudo nano /Library/LaunchDaemons/com.checkpoint.epc.service.plist I have a script that can be used here:
https://gist.github.com/cyupa/ebb2a80a699d4c2f567b78161cb28767