Docker-compose nextcloud:fpm Page not found error

Trying to install Nextcloud via docker-compose of nextcloud:fpm + mariadb with an external host configured Nginx.

I have followed config for Ubuntu installed Nginx for Nextcloud FPM then I have used the suggested docker-compose setup from the nextcloud maintained repo (removing the “web” section)

So Nginx on the host, nextcloud:fpm in a container. Everything launches without error but I get “Page not found” when I hit the URL.

Could there be a problem in configuring Nginx to find php files that are inside the container’s file system?

I’m not sure how to reference a location that is inside the nextcloud:fpm container. I mean I know how to do the mapping, just not sure what to map.

There is a section in the docker-compose.yml that (the one WITH Nginx) where the web server is granted access to the nextcloud volumes:

      - app

So I suspect now that Nginx is external to docker-compose I need to do some explicit mapping?