Is there a way to get an Amazon web services Websocket connection through nginx that supports Hixie76 protocol?

I have a (fairly complex) django app hosted on AWS via Elastic Beanstalk, and am trying to implement websockets on it, using django-channels

Here is the docker-compose.yml file sent to elastic beanstalk:

version: "3.8"

services:
  migration:
    build: .
    env_file:
      - .env
    command: python manage.py migrate

  api:
    build: .
    env_file:
      - .env
    command: daphne myapp.asgi:application  --port 8000 --bind 0.0.0.0
    deploy:
      restart_policy:
        condition: on-failure
        delay: 5s
        max_attempts: 3
        window: 120s
    expose:
      - 8000
    depends_on:
      - migration

  nginx:
    image: nginx:1.21.0-alpine
    env_file:
      - .env
    volumes:
      - ./nginx/templates:/etc/nginx/templates
      - ./nginx/certs:/etc/nginx/certs
    ports:
      - 80:80
      - 443:443
    depends_on:
      - api
    deploy:
      restart_policy:
        condition: on-failure
        delay: 5s
        max_attempts: 3
        window: 120s

Here is the nginx config file:

server {
    listen 80;
    listen [::]:80;

    location /health/ {
        proxy_pass         http://api:8000/health/;
        proxy_set_header   Host $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-Host $server_name;
    }

    location / {
        return 301 https://$host$request_uri;
    }
}

server {
    listen 443 ssl;
    listen [::]:443 ssl;
    root /usr/share/nginx/html/;
    index index.html; 

    ssl_certificate /etc/nginx/certs/public.crt;
    ssl_certificate_key /etc/nginx/certs/myapp.pem;

    location / {
        proxy_pass         http://api:8000/;
        proxy_http_version 1.1;
        proxy_set_header   Upgrade $http_upgrade;
        proxy_set_header   Connection "upgrade";
        proxy_set_header   Host $host;
        proxy_set_header   X-Real-IP $remote_addr;
        proxy_set_header   X-Forwarded-Host $server_name;
        proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header   X-Forwarded-Proto https;
        proxy_read_timeout 300s;
    }

    client_max_body_size 5M;
}

When running on my local machine, everything runs smooth. but after deployment of this configuration on an EC2 instance, when I try to connect to my websocket using:

var websocket = new WebSocket('wss://my-app.com/ws/room/13/');

All I get from my nginx logs is the following (nothing is outputed in my django logs):

ZZZ.ZZ.ZZ.ZZ - - [03/May/2023:15:16:34 +0000] "GET /ws/room/13/ HTTP/1.1" 400 5 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/111.0" "XX.XXX.XX.XX, YY.YYY.YYY.YY"

If I turn debug on nginx, I can isolate the following error:

2023/05/03 15:16:34 [debug] 36#36: *21 http proxy status 400 "400 WebSocket connection denied - Hixie76 protocol not supported."

An error which doesn’t provide much information online… I have tried every websocket client I could find, and this is still the error I am getting.

Does anyone have a clue about what is happening?