diff --git a/frontend/src/types/yaml.ts b/frontend/src/types/yaml.ts
index 02758f0..8e1e78e 100644
--- a/frontend/src/types/yaml.ts
+++ b/frontend/src/types/yaml.ts
@@ -34,4 +34,7 @@ export interface YamlNode {
   bottomHandles?: number
   leftHandles?: number
   rightHandles?: number
+  // Whether port-number labels are shown next to connection points. Only written
+  // when enabled so the toggle round-trips through export/import (issue #272).
+  showPortNumbers?: boolean
 }
diff --git a/frontend/src/utils/__tests__/exportYaml.test.ts b/frontend/src/utils/__tests__/exportYaml.test.ts
index 83a4ff2..c87afa6 100644
--- a/frontend/src/utils/__tests__/exportYaml.test.ts
+++ b/frontend/src/utils/__tests__/exportYaml.test.ts
@@ -208,4 +208,12 @@ describe('exportCanvasToYaml', () => {
     expect(entry).not.toHaveProperty('topHandles')
     expect(entry).not.toHaveProperty('leftHandles')
   })
+
+  it('exports showPortNumbers only when enabled (issue #272)', () => {
+    const on = (yaml.load(exportCanvasToYaml([makeNode({ label: 'On', type: 'server', show_port_numbers: true })], [])) as Record<string, unknown>[])[0]
+    expect(on.showPortNumbers).toBe(true)
+
+    const off = (yaml.load(exportCanvasToYaml([makeNode({ label: 'Off', type: 'server', show_port_numbers: false })], [])) as Record<string, unknown>[])[0]
+    expect(off).not.toHaveProperty('showPortNumbers')
+  })
 })
diff --git a/frontend/src/utils/__tests__/importYaml.test.ts b/frontend/src/utils/__tests__/importYaml.test.ts
index 6b4db95..dfc481e 100644
--- a/frontend/src/utils/__tests__/importYaml.test.ts
+++ b/frontend/src/utils/__tests__/importYaml.test.ts
@@ -368,4 +368,30 @@ describe('parseYamlToCanvas', () => {
     expect(edges[0].targetHandle).toBe('top-t')
     expect(nodes.find((n) => n.data.label === 'Switch')!.data.bottom_handles).toBe(3)
   })
+
+  // Regression for issue #272.
+  it('restores the show-port-numbers toggle from YAML', () => {
+    const yaml = `
+- nodeType: server
+  label: "Server"
+  showPortNumbers: true
+`
+    const { nodes } = parseYamlToCanvas(yaml, empty, emptyEdges)
+    expect(nodes.find((n) => n.data.label === 'Server')!.data.show_port_numbers).toBe(true)
+  })
+
+  it('round-trips show-port-numbers through export → import (issue #272)', () => {
+    const on: Node<NodeData> = {
+      id: 'on', type: 'server', position: { x: 0, y: 0 },
+      data: { label: 'On', type: 'server', status: 'online', services: [], show_port_numbers: true },
+    }
+    const off: Node<NodeData> = {
+      id: 'off', type: 'server', position: { x: 0, y: 0 },
+      data: { label: 'Off', type: 'server', status: 'online', services: [] },
+    }
+    const yamlStr = exportCanvasToYaml([on, off], [])
+    const { nodes } = parseYamlToCanvas(yamlStr, empty, emptyEdges)
+    expect(nodes.find((n) => n.data.label === 'On')!.data.show_port_numbers).toBe(true)
+    expect(nodes.find((n) => n.data.label === 'Off')!.data.show_port_numbers).toBeUndefined()
+  })
 })
diff --git a/frontend/src/utils/exportYaml.ts b/frontend/src/utils/exportYaml.ts
index f2a9772..75ef513 100644
--- a/frontend/src/utils/exportYaml.ts
+++ b/frontend/src/utils/exportYaml.ts
@@ -92,6 +92,9 @@ export function exportCanvasToYaml(nodes: Node<NodeData>[], edges: Edge<EdgeData
     // Custom connection-point counts, so imported edges land on real slots.
     attachHandleCounts(entry, d)
 
+    // Preserve the port-number toggle so it survives a round-trip (issue #272).
+    if (d.show_port_numbers) entry.showPortNumbers = true
+
     // Parent relationship: if this node has a parentId in React Flow,
     // encode it as a 'parent' connection using any virtual edge between them.
     if (node.parentId) {
diff --git a/frontend/src/utils/importYaml.ts b/frontend/src/utils/importYaml.ts
index 5332d48..9c1ea00 100644
--- a/frontend/src/utils/importYaml.ts
+++ b/frontend/src/utils/importYaml.ts
@@ -79,6 +79,8 @@ export function parseYamlToCanvas(
       ...(yn.bottomHandles ? { bottom_handles: yn.bottomHandles } : {}),
       ...(yn.leftHandles ? { left_handles: yn.leftHandles } : {}),
       ...(yn.rightHandles ? { right_handles: yn.rightHandles } : {}),
+      // Restore the port-number toggle (issue #272).
+      ...(yn.showPortNumbers ? { show_port_numbers: true } : {}),
     }
 
     newNodes.push({