Create Sub-Domain for a backend server

[congdaoduy298]

Hi, community.
I want to create a subdomain for my backend server. Currently, I have a frontend app on port 3000 and a backend server on port 3001 (they’re on the same device). I configured my router to port forward port 3000 to port 80 (router) and port 3001 to port 8080 (router).
It’s working fine on myPublicIP:80 and myPublicIP:8080. My frontend app with the domain is okay, but I cannot use NGINX to set up sub.domain and listen to port 8080. I see that every sub.domain will go to port 80 on the router and then to port 3000 on my localhost, regardless of what I set up on NGINX. Is there any way to configure it?
Thank you.

[congdaoduy298]

Cloudflare Tunnel solved my problem. Thank you everyone reading this.