diff --git a/frontend/src/pages/NetworkDiagrams/DiagramEditor.tsx b/frontend/src/pages/NetworkDiagrams/DiagramEditor.tsx
index e10629fc..635be4fe 100644
--- a/frontend/src/pages/NetworkDiagrams/DiagramEditor.tsx
+++ b/frontend/src/pages/NetworkDiagrams/DiagramEditor.tsx
@@ -28,6 +28,11 @@ import { toast } from '@/lib/toast'
 import type { DeviceTypeResponse, DeviceProperties, AIGenerateResponse, DiagramEdge, DiagramNode } from '@/types'
 import type { DeviceNodeData } from '@/components/network/nodes/DeviceNode'
 
+function normalizeZOrder(nodes: Node[]): Node[] {
+  const sorted = [...nodes].sort((a, b) => ((a.zIndex ?? 0) - (b.zIndex ?? 0)))
+  return sorted.map((n, i) => ({ ...n, zIndex: i + 1 }))
+}
+
 type ContextMenuState = {
   type: 'node' | 'canvas'
   position: { x: number; y: number }
@@ -307,7 +312,7 @@ function DiagramEditorInner() {
         connectionType: d.connectionType as string || 'ethernet',
         speed: d.speed as string || null,
         notes: d.notes as string || null,
-        routing: d.routing as string || null,
+        routing: (d.routing as DiagramEdge['routing']) || null,
       }
     })
   }, [edges])
@@ -510,19 +515,20 @@ function DiagramEditorInner() {
 
   const handleBringToFront = useCallback((nodeId: string) => {
     pushHistory(nodes, edges)
-    setNodes(nds => {
-      const maxZ = Math.max(0, ...nds.map(n => n.zIndex ?? 0))
-      return nds.map(n => n.id === nodeId ? { ...n, zIndex: maxZ + 1 } : n)
+    setNodes(prev => {
+      const maxZ = Math.max(0, ...prev.map(n => n.zIndex ?? 0))
+      return normalizeZOrder(
+        prev.map(n => n.id === nodeId ? { ...n, zIndex: maxZ + 1 } : n)
+      )
     })
     setIsDirty(true)
   }, [nodes, edges, pushHistory, setNodes])
 
   const handleSendToBack = useCallback((nodeId: string) => {
     pushHistory(nodes, edges)
-    setNodes(nds => {
-      const minZ = Math.min(0, ...nds.map(n => n.zIndex ?? 0))
-      return nds.map(n => n.id === nodeId ? { ...n, zIndex: minZ - 1 } : n)
-    })
+    setNodes(prev => normalizeZOrder(
+      prev.map(n => n.id === nodeId ? { ...n, zIndex: 0 } : n)
+    ))
     setIsDirty(true)
   }, [nodes, edges, pushHistory, setNodes])