I am using Godaddy as my domain registrar and created a <subdomain_name> which is linked to my servers IP address on Digital Ocean. I am also using Let’s encrypt to get SSL certificates and nginx as reverse proxy. Below is my nginx conf. file that I am using:

server {
        listen 443 http2 ssl;
        server_name <subdomain_name>;

        #Logging
        access_log /var/log/nginx/<subdomain_name>.access.log;
        error_log /var/log/nginx/<subdomain_name>.error.log;


        location /.well-known/acme-challenge/ {
                root /var/www/html/test; # Temp for generating letsencrypt
                default_type text/plain;
        }

        location / {
                proxy_set_header Host $host:$server_port;
                proxy_set_header X-Real-IP $remote_addr;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_set_header X-Forwarded-Proto $scheme;

                #Fix the “It appears that your reverse proxy set up is broken” error.

                proxy_pass http://127.0.0.1:3001;
                proxy_read_timeout 90;
                proxy_redirect http://127.0.0.1:3001 http://<subdomain_name>/;

                #Required for new HTTP-based CLI

                proxy_http_version 1.1;
                proxy_request_buffering off;
        }

        # SSL configuration
        ssl_certificate /etc/letsencrypt/live/<subdomain_name>/fullchain.pem; # managed by Certbot
        ssl_certificate_key /etc/letsencrypt/live/<subdomain_name>/privkey.pem; # managed by Certbot
        include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
        ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot

}

server {
        if ($host = <subdomain_name>) {
                return 301 https://$host$request_uri;
        } # managed by Certbot

        listen 80;
        server_name <subdomain_name>;
        return 404; # managed by Certbot
}

Setup:

I am running multiple applications that are listening on different ports with some applications being dependent on each other.

Example:

http://<subdomain_name>:3001 -> being a nginx application angular frontend application
http://<subdomain_name>:3002 -> an API that provides http://<subdomain_name>:3001 with the necessary data
http://<subdomain_name>:3003 -> another service

Problem:

When I run the domains without ssl using just plain http like http://<subdomain_name>:3001, http://<subdomain_name>:3002, http://<subdomain_name>:3003 then they work fine.
However when I try to run it in https, then the following cant be accessed:

https://<subdomain_name>:3002, https://<subdomain_name>:3003

The browser says:

This website cannot provide a secure connection <subdomain_name> has sent an invalid response.
ERR_SSL_PROTOCOL_ERROR

Only https://<subdomain_name>:3001 works, as it is being redirected because that is what I indicated in my nginx.conf file. However I do get a console error that says

POST https://<subdomain_name>:3002/graphql net::ERR_SSL_PROTOCOL_ERROR

The problem is that https://<subdomain_name>:3002 throws an error that it is not able to supply the data because it cant make a post request due to it not being a secure ssl connection.

I played around with the nginx config by adding different server blocks for the different services but I cant get it to work.

I want that the following will work with https as well:

http://<subdomain_name>:3001    
http://<subdomain_name>:3002
http://<subdomain_name>:3003

Also, I want that service https://<subdomain_name>:3002 is able to provide data to https://<subdomain_name>:3001 by getting rid of this error.

POST https://<subdomain_name>:3002/graphql net::ERR_SSL_PROTOCOL_ERROR