@killmasta93 said in Access Website internally?:
but wanted the Let encrypt on NGINX rather then on pfSense
"Letsencrypt"is a concept, a brand, not code.
It needs, on 'your' side, a program, most often scripts like Python, bash etc that runs on some system (OS).
NGINX is a web server; that, on request from a web browser, gets files from its local storage and send it to the browser asking for it. It does not natively execute programs or scripts.
Your NGINX runs on a device (host) : install certbot, acme.sh or whatever script you like, that interfaces with the Letenscrypt API servers. The traffic will just flow through pfSEnse, as any other traffic.