Cannot connect to bastion host in AWS

I am following the guide in https://aws-quickstart.s3.amazonaws.com/quickstart-bitnami-wordpress/doc/wordpress-high-availability-by-bitnami-on-the-aws-cloud.pdf to create a WordPress High Availability on AWS.

The creation succeeds. And I can visit the WordPress site and the admin panel. However, when I follow the instructions in section "Option 2. Connect to the cluster through SSH", I find I cannot connect to the Bastion host instance. I always get the error "Connection timed out".

Since I am using SecureCRT, not ssh or PuTTY, so I doubt that there may be some misconfiguration in SecureCRT or it does not work for Amazon EC2 instances. So I try to create a test EC2 instance, and then find I can connect to it with SecureCRT successfully, with the key pair same as that for the Bastion host.

So what I have done wrong? Or what log can I check to solve this issue?

SSH Timeout usually points to a Firewall or Security Group issue. One way or another your SecureCRT is blocked from accessing the Bastion host on the network level. Make sure that the Security Group associated with the instance has a rule that allows SSH from your external IP address.