How to deploy angular front and nodeJS back on same droplet using nginx

Hello and thank you for your help.

I have created droplet on which I want to setup my project. I have managed to set up front (Angular/Nginx) and back (NodeJS) following this tutorial> https://www.digitalocean.com/community/tutorials/how-to-set-up-a-node-js-application-for-production-on-ubuntu-16-04.

Back is working and properly connecting to my db and sending data that I can access when I type http://<server-api>:3000. Front is also working (I can access it on http://<server-api>) but not receiving data from the backend. I have tried to find a solution to the problem I have added reversed proxy to my default nginx file.

        location / {
                # First attempt to serve request as file, then
                # as directory, then fall back to displaying a 404.
                try_files $uri $uri/ =404;
                proxy_pass http://localhost:3000;
                proxy_cache_bypass $http_upgrade;

        }

but when I add this I can’t reach http://<server-api>:3000 anymore. General problem is I don’t understand how to connect front and back. Any help or instructions or what to look for next to understand problem would be welcome. Thank you!