Have two nginx basic configs

nginx/subdomain_basic_root.conf

@@ -1,4 +1,4 @@
-server {
+server{
   index index.html;
 
   root MY_ROOT;
@@ -8,10 +8,6 @@ server {
     try_files $uri $uri/;
   }
 
-  if ($host = DOMAIN) {
-      return 301 https://$host$request_uri;
-  } # managed by Certbot
-
   listen 80;
   listen [::]:80;
   return 404; # managed by Certbot

nginx/subdomain_proxy.conf

@@ -0,0 +1,27 @@
+server {
+  index index.html;
+
+  # replace with sub-domain
+  server_name DOMAIN;
+
+  location / {
+    proxy_set_header Host $http_host;
+    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+    proxy_set_header X-Forwarded-Proto $scheme;
+    proxy_set_header Upgrade $http_upgrade;
+    proxy_set_header Connection "Upgrade";
+    proxy_redirect off;
+    proxy_buffering off;
+    # replace the port that's used for the internal app
+    proxy_pass http://127.0.0.1:PORT;
+  }
+  # temporary files required for certbot
+  location /.well_known/ {
+    # replace with root for temp files (usually /var/www/html/)
+    root MY_ROOT;
+  }
+
+  listen 80;
+  listen [::]:80;
+  return 404; # managed by Certbot
+}