diff --git a/src/app/api.ts b/src/app/api.ts
index 56ecaf9..c84a6a0 100644
--- a/src/app/api.ts
+++ b/src/app/api.ts
@@ -1,6 +1,30 @@
 import { isDevMode } from '@angular/core';
 
-// QR Vitanova API (dynamic QR, settings, polling).
+export function resolveProductionApiBase(
+  hostname: string = globalThis.location?.hostname ?? ''
+): string {
+
+  if (!hostname) {
+    return 'https://qr.vitanova.network/api';
+  }
+
+  // If app is already on qr.<domain>, use the same host.
+  if (hostname.startsWith('qr.')) {
+    return `https://${hostname}/api`;
+  }
+
+  // For domains like app.paylow.online or paylow.online, target qr.paylow.online.
+  const parts = hostname.split('.').filter(Boolean);
+  if (parts.length >= 2) {
+    const rootDomain = parts.slice(-2).join('.');
+    return `https://qr.${rootDomain}/api`;
+  }
+
+  return `https://qr.${hostname}/api`;
+}
+
+// Dynamic QR API base (settings, creation, polling).
+// Dev keeps proxy for local work; production resolves from the current domain.
 export const QR_VITANOVA_API = isDevMode()
   ? '/proxy/qr-vitanova/api'
-  : 'https://qr.vitanova.network/api';
+  : resolveProductionApiBase();