title: SSH works but cannot PING and access VNC viewer for Raspberry Pi 3B
body: <p>On my Mac terminal, I can get my Pi ip address using this command line:</p>
  <p>arp -n raspberrypi.local</p>
  <p>it return the IP address of the pi.
  and then I can absolutely SSH into the raspberry pi using these command lines:</p>
  <p>ssh-keygen -R raspberrypi.local
  ssh pi@raspberrypi.local</p>
  <p>However if I ping the pi, it return request timeout and I also cannot access the vnc viewer.</p>
  <p><a href="https://i.stack.imgur.com/By8BD.png" rel="nofollow noreferrer">PING from Network Utility</a></p>
  <p>Everything worked just fine when I first log in to this raspberry pi but then this happened.</p>