title: How to access webserver running in double NAT network from external network
body: <p>This is not a programming question, more likely a network question. Sorry, If I shouldn't post this question here.</p>
  <p>I'm trying to access my webservice that controls my micro-controllers GPIO from external network using my public IP, but I couldn't able to. On little research I came to know that my ISP is using double NAT and that can't be accessible from outside network. But <code>Blynk</code> app on my mobile is able to trigger my microcontroller from outside network (by registering my microcontroller with <code>Blynk</code> cloud).</p>
  <p>My question is how <code>Blynk</code> is able to reach-out the device running behind same double NAT network.</p>
  <p>Thanks in advance.</p>