diff --git a/lxc/sparse-cone.txt b/lxc/sparse-cone.txt
index 2225a0778..c9aa78307 100644
--- a/lxc/sparse-cone.txt
+++ b/lxc/sparse-cone.txt
@@ -1,30 +1,30 @@
-# lxc/sparse-cone.txt
-# ---------------------------------------------------------------------------
-# Sparse-checkout cone list for the MeshMonitor LXC template build.
-#
-# WHAT THIS FILE CONTROLS
-#   build-lxc-template.sh reads this file at build time and passes the listed
-#   directories to git sparse-checkout set. Only these directories, plus
-#   all root-level files (package.json, tsconfig*.json, vite.config.ts, etc.),
-#   which cone mode always includes automatically, are materialized inside
-#   /opt/meshmonitor in the container rootfs. Everything else (docs/, desktop/,
-#   .github/, etc.) is never fetched, keeping the template lean (~8MB .git vs
-#   ~51MB for a full clone).
-#
-# MAINTENANCE
-#   If you add a new top-level directory that is required at runtime, add it
-#   here or the LXC template will silently omit those files on the next build.
-#   After updating: rebuild the template and confirm meshmonitor-update works.
-#
-# FOR AI ASSISTANTS
-#   This is the single source of truth for LXC template directory inclusion.
-#   Update this file in the same commit whenever you add a runtime-required
-#   top-level directory. See CLAUDE.md "LXC Template Build" for the full rule.
-# ---------------------------------------------------------------------------
-
-src
-public
-docker
-protobufs
-scripts
+# lxc/sparse-cone.txt
+# ---------------------------------------------------------------------------
+# Sparse-checkout cone list for the MeshMonitor LXC template build.
+#
+# WHAT THIS FILE CONTROLS
+#   build-lxc-template.sh reads this file at build time and passes the listed
+#   directories to git sparse-checkout set. Only these directories, plus
+#   all root-level files (package.json, tsconfig*.json, vite.config.ts, etc.),
+#   which cone mode always includes automatically, are materialized inside
+#   /opt/meshmonitor in the container rootfs. Everything else (docs/, desktop/,
+#   .github/, etc.) is never fetched, keeping the template lean (~8MB .git vs
+#   ~51MB for a full clone).
+#
+# MAINTENANCE
+#   If you add a new top-level directory that is required at runtime, add it
+#   here or the LXC template will silently omit those files on the next build.
+#   After updating: rebuild the template and confirm meshmonitor-update works.
+#
+# FOR AI ASSISTANTS
+#   This is the single source of truth for LXC template directory inclusion.
+#   Update this file in the same commit whenever you add a runtime-required
+#   top-level directory. See CLAUDE.md "LXC Template Build" for the full rule.
+# ---------------------------------------------------------------------------
+
+src
+public
+docker
+protobufs
+scripts
 lxc
\ No newline at end of file
diff --git a/src/server/meshcoreManager.contactPersistence.test.ts b/src/server/meshcoreManager.contactPersistence.test.ts
index 2a862fbb6..80bcb1e24 100644
--- a/src/server/meshcoreManager.contactPersistence.test.ts
+++ b/src/server/meshcoreManager.contactPersistence.test.ts
@@ -284,4 +284,48 @@ describe('MeshCoreManager contact persistence (issue #3092)', () => {
       advType: MeshCoreDeviceType.REPEATER,
     });
   });
+
+  it('keeps the known name when a later advert has an empty adv_name (issue #3756)', async () => {
+    const manager = new MeshCoreManager('src-a');
+
+    // First advert carries the real name.
+    dispatchBridgeEvent(manager, {
+      event_type: 'contact_advertised',
+      data: {
+        public_key: REPEATER_PUBKEY,
+        adv_name: 'MyRepeater',
+        adv_type: MeshCoreDeviceType.REPEATER,
+      },
+    });
+    await Promise.resolve();
+    await Promise.resolve();
+
+    // Second advert (e.g. a zero-hop repeater) arrives with an empty name.
+    // With `??` this would overwrite the stored name with ""; `||` keeps it.
+    dispatchBridgeEvent(manager, {
+      event_type: 'contact_advertised',
+      data: {
+        public_key: REPEATER_PUBKEY,
+        adv_name: '',
+        adv_type: MeshCoreDeviceType.REPEATER,
+      },
+    });
+    await Promise.resolve();
+    await Promise.resolve();
+
+    // In-memory contact retains the original name.
+    expect(manager.getContact(REPEATER_PUBKEY)).toMatchObject({
+      publicKey: REPEATER_PUBKEY,
+      advName: 'MyRepeater',
+    });
+
+    // The DB write from the empty-name advert also preserves the name.
+    expect(upsertNode).toHaveBeenLastCalledWith(
+      expect.objectContaining({
+        publicKey: REPEATER_PUBKEY,
+        name: 'MyRepeater',
+      }),
+      'src-a',
+    );
+  });
 });
diff --git a/src/server/meshcoreManager.ts b/src/server/meshcoreManager.ts
index e2d1d8adc..108c3f571 100644
--- a/src/server/meshcoreManager.ts
+++ b/src/server/meshcoreManager.ts
@@ -1109,7 +1109,10 @@ class MeshCoreManager extends EventEmitter {
         const updated: MeshCoreContact = {
           ...existing,
           publicKey,
-          advName: data.adv_name ?? existing.advName,
+          // `||` not `??`: zero-hop repeaters (and some firmware builds) emit
+          // `contact_advertised` with adv_name === "", which `??` would pass
+          // through and overwrite the known name with an empty string (#3756).
+          advName: data.adv_name || existing.advName,
           advType: data.adv_type ?? existing.advType,
           lastAdvert: data.last_advert ?? existing.lastAdvert,
           latitude: data.latitude ?? existing.latitude,
@@ -1470,7 +1473,9 @@ class MeshCoreManager extends EventEmitter {
       await databaseService.meshcore.upsertNode(
         {
           publicKey: contact.publicKey,
-          name: contact.advName ?? contact.name ?? null,
+          // `||` not `??` so an empty advName falls back to name rather than
+          // persisting "" into the node row (#3756).
+          name: contact.advName || contact.name || null,
           advType: contact.advType ?? null,
           latitude: atNullIsland ? null : (contact.latitude ?? null),
           longitude: atNullIsland ? null : (contact.longitude ?? null),