I am not able to connect my instances by clicking the connect button.

When you're experiencing connection issues with EC2 Instance Connect, there are several potential causes to investigate:

1. Security Group Configuration: The most common issue is that your security group doesn't allow inbound SSH traffic (port 22) from the EC2 Instance Connect IP range for your specific region. You need to add an inbound rule to your security group allowing SSH traffic from the EC2 Instance Connect IP range.

2. Network Configuration: Verify that your instance is in a public subnet with an internet gateway attached, allowing for the necessary outbound traffic.

3. Instance Status: Check if your instance is fully running and if all status checks are passing. A failing status check could indicate an OS-level issue preventing connections.

4. EC2 Instance Connect Prerequisites: Ensure the EC2 Instance Connect package is installed on your instance if you're using a supported Linux distribution.

5. IAM Permissions: Verify that your IAM user or role has the necessary permissions to use EC2 Instance Connect.

Troubleshooting steps:

• Try stopping and starting your EC2 instance (not just rebooting)
• Double-check your security group's inbound rules to ensure they allow traffic from the EC2 Instance Connect IP range
• Verify your VPC and subnet configurations for proper internet connectivity
• Consider using alternative connection methods like AWS Systems Manager Session Manager if SSH continues to fail

If you've verified all these settings and still can't connect, it might be worth reaching out to AWS support for more in-depth troubleshooting assistance.
Sources
EC2 Instance Connect Fails to Connect - Network Configuration Issues or Misconfiguration? | AWS re:Post
EC2 Instance Connect cannot connect to my instance ! | AWS re:Post
EC2 instance failed to connet | AWS re:Post
Facing problem while connecting ec2 instance | AWS re:Post

I have checked all the above mentioned troubleshooting steps. Everything is fine. Still i am facing the issue.

Assuming your EC2 is up and running without status check failures,

• can you check if your IAM permissions allow EC2 operations.
• as a quick test, give your account ec2:* permissions temporarily to see if you can connect.

Yes EC2 permission are allowed in IAM. Still issue is there

I am having the same issue at the moment. I've tried various AMI's but to no avail. I've been having this issue for some time but I left it thinking it would eventually resolve itself but it hasn't.

Anyone please help. @AWS team : I am sure that there is something wrong from AWS side.