There is a domain, how to specify that the subdomain would address the current to a specific port?

Question

Domain Name System

I bought a domain and hosting on reg.ru I
have a domain, I left it on the hosting.
Created a subdomain. aaa.aaa.ru indicated its ip 11.1.1.1 in domain records
But how to make the aaa.aaa.ru subdomain address not on ip 11.1.1.1 entirely to the server, but on 11.1.1.1:900 current to a specific port.

Answer 1

There is no port separation in DNS records.

Answer 2

Port forwarding - take any web server (nginx, Apache) and configure port forwarding 80 (or 443 if ssl) to the desired local