I have set up a frontend application (React) and a backend application(Java—Spring Boot) on my droplet. I am running an Nginx webserver with SSL certification.

I can't get my front end to call my back end. I have tried changing the URL to my DNS and different ports. I have also tried HTTP and HTTPS on both the frontend call and the backend corsRegistry.

I feel like it should be easy for my backend and frontend to connect, since they are on the same droplet, but I'm having a very hard time.

#Here is my Backend webConfig:

public class WebConfig implements WebMvcConfigurer {
    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**")
                .allowedOrigins("https://www.pligtlisten.dk", "http://localhost:3000")
                .allowedMethods("GET", "POST", "PUT", "DELETE")
                .allowCredentials(true);
    }
}

#Here is my docker-compose file:

version: '3.8'
services:
  web:
    build:
      context: .
      dockerfile: Dockerfile
    ports:
      - "80:80"  
      - "443:443" 
    volumes:
      - /etc/letsencrypt/live/www.pligtlisten.dk/fullchain.pem:/etc/letsencrypt/live/www.pligtlisten.dk/fullchain.pem:ro
      - /etc/letsencrypt/live/www.pligtlisten.dk/privkey.pem:/etc/letsencrypt/live/www.pligtlisten.dk/privkey.pem:ro
    restart: unless-stopped

#Here is my docker file:

FROM node:18-alpine AS build
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
RUN npm run build

FROM nginx:alpine
COPY --from=build /app/build /usr/share/nginx/html
COPY nginx.conf /etc/nginx/conf.d/default.conf
EXPOSE 80
CMD ["nginx", "-g", "daemon off;"]

#Here is my nginx server settings:

server {
    listen 80;
    server_name www.pligtlisten.dk pligtlisten.dk;
    return 301 https://www.pligtlisten.dk$request_uri;
}

server {
    listen 443 ssl;
    server_name www.pligtlisten.dk pligtlisten.dk;

    ssl_certificate /etc/letsencrypt/live/www.pligtlisten.dk/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/www.pligtlisten.dk/privkey.pem;
    ssl_protocols TLSv1.2 TLSv1.3;
    ssl_prefer_server_ciphers on;
    ssl_ciphers EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH;
    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;

    location / {
        root /usr/share/nginx/html;
        index index.html index.htm;
        try_files $uri $uri/ /index.html;
    }
}

#This is the url i am using right now from frontend to reach backend:

export const BASE_URL = "https://161.35.196.6:8080";
export const GOOGLE_ACCOUNT_ENDPOINT = `${BASE_URL}/googleAccount`;
export const POINT_SCORE_ENDPOINT = `${BASE_URL}/pointScore`;