You could use a reverse proxy like Nginx to route your subdomains.
Here is an example of nginx configuration, you might probaly have to complete according to your project and server :
server {
    listen          80;
    server_name     corporatewebsite.com;
    location / {
        [ ... some parameters ... ]
        include         proxy_params; // Import global configuration for your routes
        proxy_pass      http://localhost:1234/; // One of your server that listens to 1234
    }
}
server {
    listen          80;
    server_name     sub.corporatewebsite.com;
    location / {
        [ ... some parameters ... ]
        include         proxy_params;
        proxy_pass      http://localhost:4567/; // The other server that listens to 4567
    }
}
You have to configure, for example, apache2 listening to port 1234 while nodejs is listening to port 4567.
If you do like this, a good practice is to block direct access from the outside to your ports 1234 and 4567 (using iptables for example).
I think this post could be useful to you : Node.js + Nginx - What now?