Subdomain with Nginx example below not working

Hi guys! I'm trying to find some example about to make a simple subdomain Nginx config but unfortunately i can't find any example to make it works in my project.

Basically i have a subdomain: bola.mytab.com.br
running in a custom port using this command:
rails lift --prod --port 3012

and after to install my certbot in a available sites with the same name: bola.mytab.com.br i also configured my nginx file this way:
could you help me please? thank you so much!

upstream app {
server http://127.0.0.1:3012;
}
server {

server_name bola.mytab.com.br;
location /app/ {
proxy_pass http://127.0.0.1:3012;
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 https;
proxy_set_header X-Forwarded-Server $host;
proxy_set_header Host $http_host;
proxy_redirect off;
}

error_page 500 502 503 504 /500.html;
client_max_body_size 4G;
keepalive_timeout 10;

listen 443 ssl; # managed by Certbot
ssl_certificate /etc/letsencrypt/live/bola.mytab.com.br/fullchain.pem; # managed by Certbot
ssl_certificate_key /etc/letsencrypt/live/bola.mytab.com.br/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 ($host = bola.mytab.com.br) {
return 301 https://$host$request_uri;
} # managed by Certbot

listen 80;
server_name bola.mytab.com.br;
return 404; # managed by Certbot
}

Start with the supplied Nginx server block and the application endpoint launched by `rails lift --prod --port 3012`; verify the request path and proxy behavior for `bola.mytab.com.br`. Done would be a reproducible configuration that serves the subdomain successfully over HTTPS, but the issue names no repository file or test to run.

Written by the indexing model from the issue text.