Django, React, Docker: Bad Request 400 when connecting to Django app.

I am trying to set up a Django back-end, with a React front-end, both running inside a Docker container, using docker-compose to expose them at different ports (8000 for the Django app, 3000 for the React app. When I navigate to http://my_ip_address:3000/ the React app loads just fine, but when I navigate to http://my_ip_address:8000 I get a 400 Bad Request error from the server. Here is the code ->

#project/back-end/Dockerfile

FROM python:3.7

ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1

WORKDIR /nerdrich

COPY Pipfile Pipfile.lock /nerdrich/
RUN pip install pipenv && pipenv install --system

COPY . /nerdrich/
EXPOSE 8000

#project/front-end/Dockerfile

# official node.js runtime for Docker
FROM node:12
# Create and set the directory for this container
WORKDIR /app/
# Install Application dependencies
COPY package.json yarn.lock /app/
RUN yarn install --no-optional
# Copy over the rest of the project
COPY . /app/

# Set the default port for the container
EXPOSE 3000

CMD yarn start

#project/docker-compose.yml

version: "3"

services:
  web:
    build: ./back-end
    command: python /nerdrich/manage.py runserver 0.0.0.0:8000
    volumes:
      - ./back-end:/nerdrich
    ports:
      - "8000:8000"
    stdin_open: true
    tty: true
  client:
    build: ./front-end
    volumes:
      - ./front-end:/app
      - /app/node_modules
    ports:
      - '3000:3000'
    stdin_open: true
    environment:
      - NODE_ENV=development
    depends_on:
      - "web"
    command:
      yarn start

#project/back-end/nerdrich/.env

ALLOWED_HOSTS=['165.227.82.162']

I can provide any additional information you need, and as I said, the front-end works just fine, it is just the back-end that gives the 400 Bad Request error.