@brave-angle-33257 really THANKS for your comments!
I got the real cause of my problem, ec2 user-data script, because ubuntu 20.04 supports only python3 http.server, not python SimpleHTTPServer☹️
Now my load balancer is healthy, and I got really a little more exact view for VPC, ALB, Ports. It’s bit annoying, but interesting!
You’re comment for ssm and ports really save me. Thanks to you again.