Docker network configuration endpoints - docker

Question

I want to know how to configure correctly the backend endpoint.
I have a docker images that runs different containers:
Backend
Frontend
Nginx for backend
DB
From my understanding, since all containers are running on the same machine, I should be able to reach the backend with "host.docker.internal".
Indeed I can successfully do it on the local machine where Docker is running on.
By the way the frontend is not able to resolve the endpoint "host.docker.internal" if I try to make a request from another machine. Please note that I'm able to reach the frontend from another machine, it's just a matter of endpoint configuration.
Note that "192.168.1.11" is the IP of the machine where Docker is running, and "8888" it's the port where the frontend is.
Obviously I can succesfully make the requests from other machines too if I put the static IP address instead of "host.docker.internal". But the question is: since the React frontend application is served on Docker itself, shouldn't it be able to resolve the "host.docker.internal" endpoint?
Just for reference, here it is my docker compose:
version: "3.8"
services:
db: #mysqldb
image: mysql:5.7
container_name: ${DB_SERVICE_NAME}
restart: unless-stopped
environment:
MYSQL_DATABASE: ${DB_DATABASE}
MYSQL_ROOT_PASSWORD: ${DB_PASSWORD}
MYSQL_PASSWORD: ${DB_PASSWORD}
MYSQL_USER: ${DB_USERNAME}
SERVICE_TAGS: dev
SERVICE_NAME: mysql
ports:
- $MYSQLDB_LOCAL_PORT:$MYSQLDB_DOCKER_PORT
volumes:
- ./docker-compose/mysql:/docker-entrypoint-initdb.d
networks:
- backend
mrmfrontend:
build:
context: ./mrmfrontend
args:
- REACT_APP_API_BASE_URL=$CLIENT_API_BASE_URL
- REACT_APP_BACKEND_ENDPOINT=$REACT_APP_BACKEND_ENDPOINT
- REACT_APP_FRONTEND_ENDPOINT=$REACT_APP_FRONTEND_ENDPOINT
- REACT_APP_FRONTEND_ENDPOINT_ERROR=$REACT_APP_FRONTEND_ENDPOINT_ERROR
- REACT_APP_CUSTOMER=$REACT_APP_CUSTOMER
- REACT_APP_NAME=$REACT_APP_NAME
- REACT_APP_OWNER=""
ports:
- $REACT_LOCAL_PORT:$REACT_DOCKER_PORT
networks:
- frontend
volumes:
- ./docker-compose/nginx/frontend:/etc/nginx/conf.d/
app:
build:
args:
user: admin
uid: 1000
context: ./MRMBackend
dockerfile: Dockerfile
image: backend
container_name: backend-app
restart: unless-stopped
working_dir: /var/www/
volumes:
- ./MRMBackend:/var/www
networks:
- backend
nginx:
image: nginx:alpine
container_name: backend-nginx
restart: unless-stopped
ports:
- 8000:80
volumes:
- ./MRMBackend:/var/www
- ./docker-compose/nginx/backend:/etc/nginx/conf.d/
networks:
- backend
- frontend
volumes:
db:
networks:
frontend:
driver: bridge
backend:
driver: bridge
The endpoint is configured in this way in the .env:
REACT_APP_BACKEND_ENDPOINT="http://host.docker.internal:8000"