Private Subnet Internet access in AWS.

Below are the things, one need to check.

• Disable the source/destination check on the NAT instance.
• Check the Security Group of the NAT instance such that they allow the incoming connection from the private subnet and allow the outbound connection for HTTP/HTTPS ports.
• Configure the NAT instance in the route table of the  private subnet.
• Both public and private instance security groups allows HTTP and HTTPS traffic.