EC2: Error establishing SSH connection to your instance. Please wait and try again later.

I am assuming you are either using "EC2 Instance connect" or "Sessions Manager" here. Have you checked if the port 22 is open to allow traffic from your IP? Here are some steps on how to check

1/ Check the inbound security groups of the instance to see if the port is open and allowing traffic from your IP

2/ You could use steps listed in "SSH client" section of connect to see if you can connect from your local machine. This will confirm your instance has connectivity.

3/ If the above step works and you want to connect using EC2 instance connect, verify task 2 and 4 of the following. https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-connect-set-up.html

4/ If you are using "Sessions Manager" - Check to make sure the following steps are in place - https://docs.aws.amazon.com/systems-manager/latest/userguide/session-manager-getting-started.html

I was having the same error while establishing connection with EC2 Instance connect, but I was able to connect using SSH client. I tried all the recommended steps from the troubleshoot guide but none of them made it work. What solved the problem was adjusting the clock on my laptop to the same time as my amazon region where I have my instance. I live in Brisbane but my closest amazon region is Sydney which is 1 hour ahead of Brisbane. Adjusting the time on my laptop to Sydney time did the trick. Now I can connect either using EC2 Instance Connect or SSH Client. Hope it helps

I assume you have the keychain? Are you able to connect via SSH using PuTTY or alternative? May be the SSH service isn't running so a restart may be required. Have you tried using SSM?

Hello, I'm seeing exactly same error, is there a solution? With same key pair, subnet and security group, I'm able to connect to another instance, but this instance keep seeing "Failed to connect to your instance Error establishing SSH connection to your instance. Try again later." when trying to connect from EC2 instance Connect. SSH Client shows similar error "Permission denied (publickey,gssapi-keyex,gssapi-with-mic).".

If you were establishing instance from AMI template please be sure you are using good username for connetion. I was also stuck with it for 20 minutes. Here are some exaples : https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/TroubleshootingInstancesConnecting.html

The issue you're encountering while trying to establish an SSH connection to your EC2 instance might be due to a few potential reasons:

1. Security Group Configuration: Check your EC2 instance's security group rules. Make sure you've allowed inbound SSH traffic (usually on port 22) from your IP address.
2. Key Pair: Verify if you are using the correct private key that corresponds to the key pair associated with the EC2 instance.
3. Network Accessibility: Ensure that your instance is in a subnet with a route to an Internet Gateway (IGW) if you're trying to connect from the internet. Also, check your Network Access Control Lists (NACLs) and confirm they're allowing inbound and outbound traffic.
4. SSH Server: The SSH server on your instance might not be running or may be misconfigured. If possible, try connecting to the instance's console and checking the SSH server logs for more details.

If you've checked all of these and you're still having trouble, it would be helpful to get more information about your setup (instance type, AMI, network configuration) to help troubleshoot further.

You might check the following article: Get started with EC2 Instance Connect

At the end of the article, there is a section which explains how to troubleshoot one common issue with EC2 Instance Connect via Web Browser. The most common issue is that your Security Group does not have entry for SSH access from Instance Connect API IP address range.