Docker network communication issue with multiple node server container-intercommunication - node.js

Question

I'm trying to setup a docker environment in which multiple containers communicate with each other via REST. My simplified system architecture looks somewhat like this:
Let's say I have two services foo and bar, that run on a node server (NestJS projects). The Dockerfile for both look something like this:
FROM node:14-alpine
ENV NODE_ENV=production \
NPM_CONFIG_PREFIX=/home/node/.npm-global \
PATH=$PATH:/home/node/.npm-global/bin:/home/node/node_modules/.bin:$PATH
RUN apk add --no-cache tini
RUN apk add iputils
RUN mkdir -p /usr/src/app/node_modules
RUN chown -R node:node /usr/src/app
USER node
WORKDIR /usr/src/app
COPY --chown=node:node package*.json ./
RUN npm ci --only=production
RUN npm cache clean --force
COPY --chown=node:node . ./
RUN ls -l
EXPOSE 80
ENTRYPOINT ["/sbin/tini", "--"]
CMD [ "npm", "start" ]
The docker-compose looks like this:
version: "3.8"
services:
foo:
image: "node:14-slim"
container_name: foo-service.${ENV}
build:
context: .
dockerfile: Dockerfile
args:
env: ${ENV}
port: ${PORT}
user: "node"
working_dir: /usr/src/app
environment:
- NODE_ENV=production
- VERSION=1.0
volumes:
- .:/usr/src/app
- /usr/app/node_modules
ports:
- ${PORT}:80
tty: true
command: "npm start"
networks:
my-network:
aliases:
- foo-service.${ENV}
networks:
my-network:
driver: "bridge"
name: my-network
I connect the containers via the my-network and made sure (docker network inspect my-network) that both containers share the same network. I can even ping one another (docker exec [foo] ping [bar])
When I'm running the application (making a REST call from the web interface) to foo, foo is then unable to "connect" to bar. I call bar from foo using the alias like this:
this.httpService.get('http://bar-service.dev:3002/...').
I get this error message:
I guess the containers still know each other since the DNS is resolved automatically by docker (I made sure that the IP-Address of bar is correct).
After some hours of trial and error and research I'd like to ask you guys. It might be an issue with alpine (some people had issues pinging node servers before). But it's also just as likely that I missed something important all along and can't seem to realize it...
Thanks in advance!