Index: src/server.js
===================================================================
--- src/server.js	(revision 09ee2bd19e715e798f3d2b165d1d90f9c37eba7d)
+++ src/server.js	(revision 5eef817483804be6a13b52f068413569df6810b0)
@@ -87,4 +87,8 @@
 const __dirname = path.dirname(fileURLToPath(import.meta.url));
 const PORT = process.env.PORT || 3000;
+// Interface to bind. Default 0.0.0.0 (needed for Docker port-forwarding). Behind a
+// reverse proxy on the same host, set HOST=127.0.0.1 so the app is NOT reachable
+// directly from the internet (only via the proxy) — see README/install docs.
+const HOST = process.env.HOST || '0.0.0.0';
 const isDev = process.env.NODE_ENV !== 'production';
 
@@ -427,5 +431,5 @@
 });
 
-server.listen(PORT, () => {
+server.listen(PORT, HOST, () => {
   console.log('');
   console.log('🪶 Klonkt Beta');