title: 504 Gateway Time-out on ALB
body: <p>I created an EC2 instance with apache installed on it and allowed HTTP/SSH traffic for my system only. I was able to access Web page using public IP of EC2. Then I configured ALB with same SG, registered same EC2 instance with ALB. Tried to access Web page using DNS name of ALB, got error -504 Gateway Time-out.</p>
  
  <p>Increased time out interval to see if this resolves issue, didn't work. Then I revisited lesson and thought lets allow HTTP traffic to everyone(since it was allowed in lecture) in SG to see if it works and YES, it worked. I again changed SG to allow traffic only for my system and it failed again.</p>