diff --git a/containers/libreportal/frontend/components/apps/core/js/apps-manager.js b/containers/libreportal/frontend/components/apps/core/js/apps-manager.js
index 55fe288..41727e4 100755
--- a/containers/libreportal/frontend/components/apps/core/js/apps-manager.js
+++ b/containers/libreportal/frontend/components/apps/core/js/apps-manager.js
@@ -373,8 +373,20 @@ class AppsManager {
       const currentUrl = new URL(window.location.href);
       targetTab = currentUrl.searchParams.get('tab') || 'config';
     }
-    
-    const newUrl = window.appPath(appName, targetTab);
+
+    // Preserve the config sub-category (/app/<name>/config/<sub>) when the URL
+    // already points at THIS app's config. Without this, rebuilding the URL
+    // here strips the sub before renderAppDetail reads it back off the path, so
+    // a cold-load deep-link / refresh of e.g. /app/bookstack/config/ports always
+    // reset to the first category. Only kept for the same app — a cross-app
+    // switch intentionally starts at the first category.
+    let targetSub = null;
+    if (targetTab === 'config' && window.appPartsFromPath) {
+      const parts = window.appPartsFromPath(window.location.pathname);
+      if (parts.tab === 'config' && parts.app === appName) targetSub = parts.sub;
+    }
+
+    const newUrl = window.appPath(appName, targetTab, targetSub);
     history.pushState({}, '', newUrl);
 
     // Update app-tabbed-manager BEFORE rendering the DOM. If renderAppDetail or