Oh, Hey Clement. I just noticed that this was you!
According to an email from last November, you have a load balancer in front of Discourse, so you’ll need to get the load balancer to handle https. That would explain why let’s encrypt wasn’t turned on for your instance. You’ll want to remove the let’s encrypt certificate (and it wouldn’t hurt to not open port 443, but it doesn’t much matter). And then figure out how to make your AWS load balancer do the https.
This also explains why the ports aren’t open, as the load balancer is in the way.