Proxying to a second nginx container

I generally have 3 or 4 separate local dev envs for Drupal development and now that I'm moving from a native local environment to docker (based on docker4drupal) I'm trying to use nginx-proxy proxy URLs like dev.d7 and dev.d8 but I can't anything to work.

I have a docker-composer.json just for nginx-proxy in the root of my ~/Sites directory:

version: "2"

services:
  # Create a revers proxy to sit in front of local dev sites
  nginx-proxy:
    image: jwilder/nginx-proxy
    #net: d8_default
    ports:
      - "80:80"
      - "443:443"
    volumes:
      - /var/run/docker.sock:/tmp/docker.sock:ro
    restart: always

Then in my ~/Sites/d8 folder I have a separate docker-composer.json based on the docker-composer.json included in docker4drupal:

version: "2"

services:
  mariadb:
    image: wodby/drupal-mariadb:1.0.0
    environment:
      MYSQL_RANDOM_ROOT_PASSWORD: 1
      MYSQL_DATABASE: drupal
      MYSQL_USER: drupal
      MYSQL_PASSWORD: drupal

  php:
    image: wodby/drupal-php:7.0-1.0.0
#    image: wodby/drupal-php:5.6-1.0.0
    environment:
      PHP_SITE_NAME: dev
      PHP_HOST_NAME: localhost:8000
      PHP_SENDMAIL_PATH: /usr/sbin/sendmail -t -i -S mailhog:1025
    volumes:
      - ./:/var/www/html

  nginx:
    image: wodby/drupal-nginx:1.0.0
    environment:
      VIRTUAL_HOST: dev.d8
      NGINX_SERVER_NAME: localhost
      NGINX_UPSTREAM_NAME: php
#      NGINX_DOCROOT: web # Relative path inside the /var/www/html/ directory.
      DRUPAL_VERSION: 8 # Allowed: 7, 8.
    volumes_from:
      - php
 #   ports:
 #     - "8000:80"
 #   networks:
 #     - nginx-proxy

  pma:
    image: phpmyadmin/phpmyadmin
    environment:
      PMA_HOST: mariadb
      PMA_USER: drupal
      PMA_PASSWORD: drupal
      PHP_UPLOAD_MAX_FILESIZE: 1G
      PHP_MAX_INPUT_VARS: 1G
    ports:
     - "8001:80"

  mailhog:
    image: mailhog/mailhog
    ports:
      - "8002:8025"

I've tried all sorts of permutations of specifying ports, adding networks, exposing ports but I'm not able to browse http://dev.d8 (I get a DNS error: ERR_NAME_NOT_RESOLVED) ... Any help is hugely appreciated.

Start with the separate root and d8 Docker Compose files, especially the nginx-proxy service, VIRTUAL_HOST setting, and commented network and port sections. Run both Compose projects and inspect their container connectivity and proxy behavior; done means http://dev.d8 resolves locally and serves the Drupal site.