Nextcloud NAS Hosting, accessible from outside LAN

I’m new to Nextcloud and this forum, I apologize if this question is not the correct place to ask this but I’ve scoured Google and cannot find help with answering this question.

I have a Synology NAS running the latest DSM (7), I’ve successfully configured the LAMP stack and installed Nextcloud on the NAS, logged in and accessed the Dashboard for the users I’ve created. Finally, I can access all of the server hosted services from the Nextcloud folder while I’m inside of my network router.

My question for the forum is if anyone here has configured access to their Nextcloud server from outside of their LAN and put together an instructional that details how to set this up specifically on the Synology NAS? I’ve tried multiple paths: DDNS on the NAS and on the router (Asus), port forwarding on the NAS and on the router. All options I’ve attempted result in a “Page not Found” response when I try to connect to the server from an outside route. I can’t even troubleshoot to determine where I’m wrong with my setup, it’s quite frustrating…

Anyone that knows how to do this, any help or direction you can provide would be most appreciated. The more elementary the instruction (dumb it down), the better please and thank you!