The docker-compose setup is using traefik to terminate the SSL traffic, as well as serve the challenge file for letsencrypt so it's configured to use both 80/443.
What are you using nginx for? You should probably just add the reverse proxy setup to your nginx conf.
Sorry, I'm sure I have no idea what I am talking about. I believe nginx is part of the letsencrypt package installed through Unraid. I'm not really sure how else to interpret the remaining parts of your questions. Appreciate the help, but I'm still lost. I tried changing port 80:80 to like 82:80 and docker-compose runs the config and spins up the "proxy_1" container, but I still can't access port 4000 or 3000. I'm sure I'm just a blind monkey trying to jam a square block into a round hole.