How to enable the permission when SSHH access to AWS EC2 instance
There could be different reasons why your verification is coming up short.
As a matter of first importance, ensure that you are utilizing the right key pair. I realize it sounds unimportant however it could really be an issue in cases like these.
Check if the username that you are utilizing is right or not. For ubuntu-based AWS AMIs, the substantial username is ubuntu, on others, it's ec2-user.
Check in the event that you are interfacing with the correct host as aws permission denied publickey