diff --git a/vite.config.ts b/vite.config.ts
index 1f317a4..6bc092a 100644
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -8,13 +8,19 @@ import { devtools } from "@tanstack/devtools-vite";
 import { leanWorkerBundle } from "./vite-plugin-lean-worker-bundle";
 
 export default defineConfig(() => {
-  const port = 3001;
+  // PORT/ALLOWED_HOST are documented self-host knobs (SELF_HOSTING_DOCKER.md,
+  // compose.yaml) but were never actually read here — every deployment was
+  // silently stuck on port 3001 and this one hardcoded domain, breaking any
+  // second instance on a different domain or port. Defaults keep existing
+  // deployments that don't set these working exactly as before.
+  const port = Number(process.env.PORT) || 3001;
 
   const showDevtools = false;
 
   const allowedHosts = [
     "seo.thedomainnest.com",
-  ];
+    process.env.ALLOWED_HOST,
+  ].filter((host): host is string => Boolean(host));
 
   return {
     envPrefix: [