Hi @klapovsciuk,

You can redirect your domain to a certain port. This depends on the WebService you are using -Nginx/Apache. If you are using Nginx, you’ll need to do add a server block to your Nginx’s website config. This can be achieved by using the bellow

location /{
    proxy_pass  http://127.0.0.1:9000/;
}

Having said that, you’ll need to add it to your subdomain’s Nginx server block/config. If you are unsure how you can do that, I’ll recommend checking out he following article:

https://www.digitalocean.com/community/tutorials/how-to-set-up-nginx-server-blocks-virtual-hosts-on-ubuntu-16-04

If you are using Apache, you have two options, the first one is to add a redirection rule in your website’s .htaccess and the second one would be to do it directly in the Apache’s Vhost file. I like using the first option. In your .htaccess file, you can add the following rule

RewriteEngine on

# redirect to 3000 if current port is not 3000 and "some-prefix/" is matched
RewriteRule ^/(.*[^/])/?$ http://www.mysite.com:3000/$1/ [R=301,L]

If you want to use Apache’s Vhost file, I’ll recommend going through the following tutorial :

https://www.digitalocean.com/community/tutorials/how-to-set-up-apache-virtual-hosts-on-ubuntu-16-04

Regards,
KDSys