diff --git a/api/src/main/kotlin/nebulosa/api/connection/ConnectionEventHub.kt b/api/src/main/kotlin/nebulosa/api/connection/ConnectionEventHub.kt
index 45eb9f3cd..d492782bd 100644
--- a/api/src/main/kotlin/nebulosa/api/connection/ConnectionEventHub.kt
+++ b/api/src/main/kotlin/nebulosa/api/connection/ConnectionEventHub.kt
@@ -7,7 +7,6 @@ import nebulosa.api.mounts.MountEventHub
 import nebulosa.api.rotators.RotatorEventHub
 import nebulosa.api.wheels.WheelEventHub
 import nebulosa.indi.device.DeviceConnectionEvent
-import nebulosa.indi.device.DeviceDetached
 import nebulosa.indi.device.DeviceEvent
 import nebulosa.indi.device.DeviceEventHandler
 import nebulosa.indi.device.camera.Camera
@@ -38,13 +37,6 @@ class ConnectionEventHub(
             if (device is FilterWheel) wheelEventHub.onConnectionChanged(device)
             if (device is Rotator) rotatorEventHub.onConnectionChanged(device)
             if (device is GuideOutput) guideOutputEventHub.onConnectionChanged(device)
-        } else if (event is DeviceDetached<*>) {
-            if (device is Camera) cameraEventHub.onDeviceDetached(device)
-            if (device is Mount) mountEventHub.onDeviceDetached(device)
-            if (device is Focuser) focuserEventHub.onDeviceDetached(device)
-            if (device is FilterWheel) wheelEventHub.onDeviceDetached(device)
-            if (device is Rotator) rotatorEventHub.onDeviceDetached(device)
-            if (device is GuideOutput) guideOutputEventHub.onDeviceDetached(device)
         }
     }
 }
diff --git a/api/src/main/kotlin/nebulosa/api/devices/DeviceEventHub.kt b/api/src/main/kotlin/nebulosa/api/devices/DeviceEventHub.kt
index 4d18a170b..3b27e0958 100644
--- a/api/src/main/kotlin/nebulosa/api/devices/DeviceEventHub.kt
+++ b/api/src/main/kotlin/nebulosa/api/devices/DeviceEventHub.kt
@@ -11,7 +11,7 @@ import java.util.concurrent.TimeUnit
 
 abstract class DeviceEventHub<D : Device, E : DeviceEvent<D>>(deviceType: DeviceType) : Consumer<E>, AutoCloseable {
 
-    private val throttlers = HashMap<D, Throttler>(4)
+    private val throttlers = ConcurrentHashMap<D, Throttler>(4)
     private val listenable = ConcurrentHashMap<D, Long>(2)
 
     private val updateEventName = "$deviceType.UPDATED"
@@ -25,29 +25,22 @@ abstract class DeviceEventHub<D : Device, E : DeviceEvent<D>>(deviceType: Device
     }
 
     open fun onAttached(device: D) {
+        throttlers.computeIfAbsent(device) { Throttler() }
         sendMessage(attachedEventName, device)
     }
 
     open fun onDetached(device: D) {
         sendMessage(detachedEventName, device)
+        throttlers.remove(device)?.onComplete()
     }
 
     open fun onConnectionChanged(device: D) {
         sendUpdate(device)
     }
 
-    open fun onDeviceDetached(device: D) {
-        synchronized(throttlers) {
-            throttlers.remove(device)?.onComplete()
-        }
-    }
-
     protected open fun onNext(event: E) {
         val device = event.device ?: return
-
-        synchronized(throttlers) {
-            throttlers.getOrPut(device, ::Throttler).onNext(event)
-        }
+        throttlers[device]?.onNext(event)
     }
 
     fun listen(device: D): Boolean {