Application service available through single domain using Nginx

I have an Ubuntu-20.04 server, and I am using this to deploy multiple docker containers and using reverse proxies to host them on Nginx.

I have 2 domains linked to my server (Single Public IP). Let’s name them domain1.com and domain2.com

Now I have 2 service running on docker, Postgres (port 5432) and MySQL (port 3306)

I set up reverse proxies to translate domain1.com to localhost:5432 and domain2.com to localhost:3306:

server {
  listen        80;
  server_name   domain1.com;

  location / {
    proxy_pass  http://localhost:5432;
  }
}

server {
  listen        80;
  server_name   domain2.com;

  location / {
    proxy_pass  http://localhost:3306;
  }
}

The thing that is bothering me here is that if I try to access domain1.com:3306, the connection works which I don’t want.

I want each domain to be accessible by the service assigned to them only.

For example a telnet to domain1.com:5432 should work but a telnet to domain1.com:3306 should fail. (I hope this makes sense here)

Can someone please help me achieve this?