Access to hosted webpage on another server

Hi all,
Hoping you can help.
I have configured MIAB successfully.
I have a website that is hosted on the same network but on another server. The website is accessible via its local address 192.168.1.x. How do you configure the MIAB dns to point to this other website? Port 80 is configured on my firewall to point to MIAB to allow letsencrypt to function as its running nginx. The website on the other server is running apache.
MIAB custom dns entry has a A record configured to point to external address.

Thanx

Julian

port 80 and 443 will need to forwarded from your modem/firewall to the web server, not MIAB.

Thanks murgero,
I moved it to port 8080.