diff --git a/controller/internal/web/handlers.go b/controller/internal/web/handlers.go
index 820be6a..deb4f4c 100644
--- a/controller/internal/web/handlers.go
+++ b/controller/internal/web/handlers.go
@@ -1048,6 +1048,9 @@ func (s *Server) storagePageData() map[string]interface{} {
 func (s *Server) networkStoragePageData() map[string]interface{} {
 	data := s.settingsBaseData("storage-network", "Hálózati tárhely")
 	data["NetworkStoragePaths"] = s.networkStorageItems(context.Background())
+	// Capability banner: "no" swaps the add form for the agent-outdated notice (yes/unknown render
+	// the form — flaky states belong to the add-time gate). Short-budget probe, cache-backed.
+	data["NetAddSupport"] = s.netAddSupport()
 	return data
 }
 
diff --git a/controller/internal/web/storage_network_template_test.go b/controller/internal/web/storage_network_template_test.go
index 0a05bb5..d3a8558 100644
--- a/controller/internal/web/storage_network_template_test.go
+++ b/controller/internal/web/storage_network_template_test.go
@@ -15,6 +15,7 @@ func TestStorageNetworkTemplate_CanonicalClasses(t *testing.T) {
 	s.loadTemplates()
 	data := map[string]interface{}{
 		"Page": "storage-network", "Title": "Hálózati tárhely",
+		"NetAddSupport": "yes",
 		"NetworkStoragePaths": []networkStorageItem{
 			{Name: "media", Label: "NAS media", Protocol: "nfs", Server: "10.0.0.5", Export: "/srv/media", Path: "/mnt/felhom-drives/media", Health: "ok"},
 			{Name: "ghost", Label: "Árva megosztás: ghost", Protocol: "nfs", Server: "10.0.0.5", Export: "/srv/ghost", Path: "/mnt/felhom-drives/ghost", Health: "idle", Orphan: true},
@@ -54,3 +55,52 @@ func TestStorageNetworkTemplate_CanonicalClasses(t *testing.T) {
 		t.Error("remove action missing")
 	}
 }
+
+// --- T5 (Scenario D): capability banner replaces the add form on an old agent -------------------
+// Companion red-proof: drop the {{if eq .NetAddSupport "no"}} wrapper (always render the form) →
+// the banner-present + form-absent assertions on "no" fail.
+func TestStorageNetworkTemplate_AgentOutdatedBanner(t *testing.T) {
+	s := testServer(t)
+	s.loadTemplates()
+	render := func(support string) string {
+		t.Helper()
+		var buf bytes.Buffer
+		err := s.tmpl.ExecuteTemplate(&buf, "storage_network", map[string]interface{}{
+			"Page": "storage-network", "Title": "Hálózati tárhely",
+			"NetAddSupport": support,
+			"NetworkStoragePaths": []networkStorageItem{
+				{Name: "media", Label: "NAS media", Protocol: "nfs", Server: "10.0.0.5", Export: "/srv/media", Path: "/mnt/felhom-drives/media", Health: "ok"},
+			},
+		})
+		if err != nil {
+			t.Fatalf("render (support=%s): %v", support, err)
+		}
+		return buf.String()
+	}
+
+	const banner = "A rendszer háttérszolgáltatása (ügynök) régebbi verziójú"
+	t.Run("no → banner instead of form; list + remove intact", func(t *testing.T) {
+		html := render("no")
+		if !strings.Contains(html, banner) {
+			t.Error("the §Part-3 banner is missing on an old agent")
+		}
+		if strings.Contains(html, `id="ns-add-form"`) {
+			t.Error("the add form must NOT render on an old agent")
+		}
+		// The share list + remove action stay fully usable in every state.
+		if !strings.Contains(html, "NAS media") || !strings.Contains(html, "Eltávolítás") {
+			t.Error("share list/remove must still render under the banner")
+		}
+	})
+	for _, support := range []string{"yes", "unknown"} {
+		t.Run(support+" → form as today", func(t *testing.T) {
+			html := render(support)
+			if !strings.Contains(html, `id="ns-add-form"`) {
+				t.Errorf("the add form must render on support=%s", support)
+			}
+			if strings.Contains(html, banner) {
+				t.Errorf("the banner must NOT render on support=%s", support)
+			}
+		})
+	}
+}
diff --git a/controller/internal/web/templates/storage_network.html b/controller/internal/web/templates/storage_network.html
index 9f6296e..ff0a276 100644
--- a/controller/internal/web/templates/storage_network.html
+++ b/controller/internal/web/templates/storage_network.html
@@ -48,6 +48,13 @@
 
 <div class="settings-card">
     <h3>Hálózati tárhely hozzáadása</h3>
+    {{if eq .NetAddSupport "no"}}
+    <!-- Capability gate (agent predates the verify-before-commit add semantics): the add form is
+         withheld; the share list + remove above stay fully usable. -->
+    <div class="alert alert-warning">A rendszer háttérszolgáltatása (ügynök) régebbi verziójú, ezért új
+        hálózati tárhely most nem csatlakoztatható. A frissítés megérkezése után a funkció automatikusan
+        elérhetővé válik — a meglévő megosztások addig is működnek.</div>
+    {{else}}
     <p class="settings-card-desc">A csatlakoztatás előtt a rendszer ellenőrzi a megosztást: valóban
         csatolható-e, és tudnak-e írni rá az alkalmazások. Hiba esetén semmi nem marad félkészen beállítva.</p>
     <form id="ns-add-form" onsubmit="return netStorageAdd(event)">
@@ -93,6 +100,7 @@
         </div>
         <div id="ns-add-result" style="margin-top:1rem"></div>
     </form>
+    {{end}}
 </div>
 
 <div class="settings-card">
@@ -206,8 +214,7 @@ function netStorageRemove(name,label){
         }).catch(function(e){ alert('Hiba: '+e); });
         }});
 }
-nsToggleSmb();
-nsUpdateHostID();
+if(document.getElementById('ns-add-form')){ nsToggleSmb(); nsUpdateHostID(); } // form absent on the capability banner
 </script>
 <div id="dialog-root"></div>
 <script>