diff --git a/examples/simple_repeater/MyMesh.cpp b/examples/simple_repeater/MyMesh.cpp
index b66e1952..1de0f646 100644
--- a/examples/simple_repeater/MyMesh.cpp
+++ b/examples/simple_repeater/MyMesh.cpp
@@ -117,7 +117,10 @@ uint8_t MyMesh::handleLoginReq(const mesh::Identity& sender, const uint8_t* secr
     }
 
     MESH_DEBUG_PRINTLN("Login success!");
-    client->last_timestamp = sender_timestamp;
+    // NOTE: don't update last_timestamp here - login uses companion RTC which may differ
+    // from the app clock used for messages. Mixing the two causes silent message rejection
+    // when the companion RTC runs ahead of the app clock (see #1551).
+    // Login replay protection is already handled by hasSeen() in the mesh layer.
     client->last_activity = getRTCClock()->getCurrentTime();
     client->permissions &= ~0x03;
     client->permissions |= perms;
diff --git a/examples/simple_room_server/MyMesh.cpp b/examples/simple_room_server/MyMesh.cpp
index b6485128..75817aa4 100644
--- a/examples/simple_room_server/MyMesh.cpp
+++ b/examples/simple_room_server/MyMesh.cpp
@@ -346,7 +346,10 @@ void MyMesh::onAnonDataRecv(mesh::Packet *packet, const uint8_t *secret, const m
       }
 
       MESH_DEBUG_PRINTLN("Login success!");
-      client->last_timestamp = sender_timestamp;
+      // NOTE: don't update last_timestamp here - login uses companion RTC which may differ
+      // from the app clock used for messages. Mixing the two causes silent message rejection
+      // when the companion RTC runs ahead of the app clock (see #1551).
+      // Login replay protection is already handled by hasSeen() in the mesh layer.
       client->extra.room.sync_since = sender_sync_since;
       client->extra.room.pending_ack = 0;
       client->extra.room.push_failures = 0;
diff --git a/examples/simple_sensor/SensorMesh.cpp b/examples/simple_sensor/SensorMesh.cpp
index 59c9aa09..113f9641 100644
--- a/examples/simple_sensor/SensorMesh.cpp
+++ b/examples/simple_sensor/SensorMesh.cpp
@@ -355,7 +355,10 @@ uint8_t SensorMesh::handleLoginReq(const mesh::Identity& sender, const uint8_t*
     }
 
     MESH_DEBUG_PRINTLN("Login success!");
-    client->last_timestamp = sender_timestamp;
+    // NOTE: don't update last_timestamp here - login uses companion RTC which may differ
+    // from the app clock used for messages. Mixing the two causes silent message rejection
+    // when the companion RTC runs ahead of the app clock (see #1551).
+    // Login replay protection is already handled by hasSeen() in the mesh layer.
     client->last_activity = getRTCClock()->getCurrentTime();
     client->permissions |= PERM_ACL_ADMIN;
     memcpy(client->shared_secret, secret, PUB_KEY_SIZE);