Not able to connect to ec2 instance after associating elastic ip to it and adding proper security group

I have installed wordpress on my ubuntu16.04 LTS instance of ec2. I was able to connect to it via public DNS. But then I added the Elastic IP to the instance and tried to connect to the instance via my browser but it took a lot of time and the browser ended up saying "This site can’t be reached". I have added security group allowing the port 80 as well. Before adding elsatic IP I was accessing the ec2 instance via public dns with no errors. Is this has to do something with elastic IP.

Thanks in advance.