Change port and host using .htaccess

Question

I am trying to use mod_rewrite to basically port forward a port on a subdomain to another port on another IP.

Like this:

sub.website.com:2000 --> 123.45.67.891:3000 

How could this be accomplished using a .htaccess file with mod_rewrite?

I have tried the following but to no avail:

RewriteCond %{HTTP_HOST} ^sub.website.com$ [NC]
RewriteCond %{SERVER_PORT} ^2000$
RewriteRule ^(.*)$ https://123.45.67.891:3000/$1 [L,R=302]

Solution

Playing with your rules, I found out that HTTP_HOST includes the port number. So the rules should look like

RewriteCond %{HTTP_HOST} ^sub.website.com:2000$ [NC]
RewriteCond %{SERVER_PORT} ^2000$
RewriteRule ^(.*)$ https://123.45.67.891:3000/$1 [L,R=302]

If you want to test against server name alone, you could use %{SERVER_NAME} as @faa suggested in the comments

RewriteCond %{SERVER_NAME} ^sub.website.com$ [NC]