AWS ALB with custom domain cannot work for specific port

Question

I have a case that I do not really understand. Please help me.

I have a backend(Fargate) and frontend(Fargate). I use same ALB but different listener port to pass traffic to those instance. FrontEnd is using port 443, backend is using port 444.

I also setup the same certificate(ACM) for both Listener.

I also created record in Route53 to route to my ALB.

I also setup inbound rule to accept 443 and 444 from everywhere in the security group.

The problem is:

Everything worked find with DNS of ALB. But when using custom domain, only Frontend work with custom domain, but Backend not. Actually, I tried to use the DNS of ALB for Backend(health check api) and it's still working. But when I change to custom domain, it doesn't work.

So what is possible reason for this case. Can someone help me?

Answer 1

Sorry everyone. In my case, I found that there is a setting on CloudFlare that already blocked port 444. Thank you guys for you supporting.

Answer 2

I think your question needs more input. Can you define what is not working with the backend? do you need public access to the backend? So if you domain is exmaple.com, what have you configured in Route53 for the frontend and the backend? Is the fronten able to talk to the backend? If not, what is the endpoint set in the frontend to talk to the backend?