My EC2 Instance connection is not working

I understand how frustrating it can be when you can't connect to your EC2 instance. Here are several potential causes and solutions to help you regain access:

1. Security Group Configuration:

• Verify that your security group allows inbound SSH traffic (port 22)
• If using EC2 Instance Connect, ensure your security group allows access from the EC2 Instance Connect IP ranges for your region (not just your personal IP)

2. Network Configuration:

• Check that your instance is in a public subnet with a route to an Internet Gateway
• Verify the route table associated with your subnet has a route for 0.0.0.0/0 pointing to the Internet Gateway
• Ensure Network ACLs allow both inbound and outbound traffic on port 22

3. Instance Health:

• Check if your instance has passed all status checks in the EC2 console
• Failed status checks could indicate underlying OS issues

4. Try Alternative Connection Methods:

• If EC2 Instance Connect isn't working, try traditional SSH with your key pair
• Consider using AWS Systems Manager Session Manager if your instance is configured for it

5. Troubleshooting Steps:

• Reboot the instance from the AWS console
• If rebooting doesn't work, try stopping and starting the instance (note: this will change its public IP if you're not using an Elastic IP)
• Check if the SSH service is running properly on the instance

If you continue to experience problems after trying these steps, you might need to contact AWS support for further assistance, as there could be account-specific or regional issues that are not immediately apparent.
Sources
Can't SSH into EC2 instance anymore | AWS re:Post
I can't connect to my EC2 instance | AWS re:Post
Unable to SSH into AWS EC2 Instance – Connection Timed Out & Forgot Credentials | AWS re:Post
EC2 Instance Connect cannot connect to my instance ! | AWS re:Post
Error establishing SSH connection to your instance. Access to EC2 has been lost | AWS re:Post