Issue with location proxy_pass setting "connect() failed (111: Connection refused) while connecting to upstream" - docker-compose

Question

I have nginx and metabase in docker. When I try to access "https://MYDOMAIN/metabase" I get the error - connect() failed (111: Connection refused) while connecting to upstream, client: 60.243.254.30, server: MYDOMAIN, request: "GET /metabase/ HTTP/2.0", upstream: "http://127.0.0.1:3000/metabase/", host: "MYDOMAIN".
This works - "curl http://localhost:3000/metabase". This also works - "curl http://127.0.0.1:3000/metabase".
nginx is running fine - I am able to access other sites that are running.
What am I doing wrong in the configuration?
docker-compose.yml
-------------------
webserver:
image: nginx:1.20.0
restart: "no"
volumes:
- ./public:/var/www/html
- ./conf.d:/etc/nginx/conf.d
- ./sites-available:/etc/nginx/sites-available
- ./sites-enabled:/etc/nginx/sites-enabled
- ./ssl:/etc/nginx/ssl
ports:
- '80:80'
- '443:443'
metabase:
image: metabase/metabase:latest
container_name: metabase
restart: "no"
volumes:
- metabase-data:/LOCATION/metabase
ports:
- '3000:3000'
environment:
MB_SITE_URL: http://localhost:3000/metabase
MB_DB_TYPE: postgres
MB_DB_DBNAME: metabase
MB_DB_PORT: 5432
MB_DB_USER: xxxxx
MB_DB_PASS: yyyyyy
nginx conf.d/default.conf
--------------------------
upstream metabase {
server 127.0.0.1:3000;
}
server {
...
location /metabase/ {
proxy_pass http://metabase;
proxy_set_header Host $http_host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
break;
}
}