title: Gradle project sync failed in Android Studio 2.3.3
body: <p>I recently updated my Android Studio from 2.0 to 2.3.3. But when I imported my old projects it started showing Gradle project sync failed. Basic functionality will not work properly.</p>
  
  <p>And messages shows:</p>
  
  <blockquote>
    <p>Unknown host 'services.gradle.org'. You may need to adjust the proxy setting in Gradle.</p>
  </blockquote>
  
  <p>How can I solve this?</p>