diff --git a/library/build.gradle b/library/build.gradle
index 12d7d23..f6fb58b 100644
--- a/library/build.gradle
+++ b/library/build.gradle
@@ -8,7 +8,7 @@ signing {
     sign configurations.archives
 }
 
-def lib_version = '1.3.6'
+def lib_version = '1.3.7'
 def user_name = 'wandersnail'
 def lib_group = 'cn.wandersnail'
 def lib_artifact = 'easyble-x'
diff --git a/library/src/main/java/cn/wandersnail/ble/ConnectionConfiguration.java b/library/src/main/java/cn/wandersnail/ble/ConnectionConfiguration.java
index 3f1cca3..7f29584 100644
--- a/library/src/main/java/cn/wandersnail/ble/ConnectionConfiguration.java
+++ b/library/src/main/java/cn/wandersnail/ble/ConnectionConfiguration.java
@@ -38,7 +38,7 @@ public class ConnectionConfiguration {
      */
     boolean useAutoConnectAfterConnectionFailure = true;
     @RequiresApi(Build.VERSION_CODES.M)
-    int transport = BluetoothDevice.TRANSPORT_LE;
+    int transport = BluetoothDevice.TRANSPORT_AUTO;
     @RequiresApi(Build.VERSION_CODES.O)
     int phy = BluetoothDevice.PHY_LE_1M_MASK;
     @NonNull
diff --git a/library/src/main/java/cn/wandersnail/ble/ConnectionImpl.java b/library/src/main/java/cn/wandersnail/ble/ConnectionImpl.java
index b712abb..3c34def 100644
--- a/library/src/main/java/cn/wandersnail/ble/ConnectionImpl.java
+++ b/library/src/main/java/cn/wandersnail/ble/ConnectionImpl.java
@@ -355,6 +355,7 @@ private void doOnConnectionStateChange(int status, int newState) {
                 logE(Logger.TYPE_CONNECTION_STATE, "GATT error! [status: %d, name: %s, addr: %s]",
                         status, device.name, device.address);
                 connectFailed = true;
+                notifyConnectionError(status);
                 if (status == 133) {
                     doClearTaskAndRefresh();
                 } else {
@@ -382,6 +383,7 @@ private void doOnServicesDiscovered(int status) {
                 }
             } else {
                 connectFailed = true;
+                notifyConnectionError(status);
                 doClearTaskAndRefresh();
                 logE(Logger.TYPE_CONNECTION_STATE, "GATT error! [status: %d, name: %s, addr: %s]",
                         status, device.name, device.address);
@@ -982,6 +984,14 @@ private void logD(int type, String format, Object... args) {
         log(Log.DEBUG, type, format, args);
     }
 
+    private void notifyConnectionError(int status) {
+        MethodInfo info = MethodInfoGenerator.onConnectionError(status);
+        observable.notifyObservers(info);
+        if (observer != null) {
+            posterDispatcher.post(observer, info);
+        }
+    }
+    
     private void notifyRequestFailed(GenericRequest request, int failType) {
         MethodInfo info = MethodInfoGenerator.onRequestFailed(request, failType, request.value);
         handleCallbacks(request.callback, info);
diff --git a/library/src/main/java/cn/wandersnail/ble/EventObserver.java b/library/src/main/java/cn/wandersnail/ble/EventObserver.java
index 914f8cd..63550c8 100644
--- a/library/src/main/java/cn/wandersnail/ble/EventObserver.java
+++ b/library/src/main/java/cn/wandersnail/ble/EventObserver.java
@@ -143,4 +143,11 @@ default void onConnectFailed(@NonNull Device device, int failType) {
      */
     default void onConnectTimeout(@NonNull Device device, int type) {
     }
+
+    /**
+     * 连接错误
+     * 
+     * @param status 状态码
+     */
+    default void onConnectionError(int status) {}
 }
diff --git a/library/src/main/java/cn/wandersnail/ble/MethodInfoGenerator.java b/library/src/main/java/cn/wandersnail/ble/MethodInfoGenerator.java
index 7717697..80e4b0a 100644
--- a/library/src/main/java/cn/wandersnail/ble/MethodInfoGenerator.java
+++ b/library/src/main/java/cn/wandersnail/ble/MethodInfoGenerator.java
@@ -23,6 +23,10 @@ static MethodInfo onConnectFailed(Device device, int failType) {
                 new MethodInfo.Parameter(int.class, failType));
     }
 
+    static MethodInfo onConnectionError(int status) {
+        return new MethodInfo("onConnectionError", new MethodInfo.Parameter(int.class, status));
+    }
+
     static MethodInfo onConnectTimeout(Device device, int type) {
         return new MethodInfo("onConnectTimeout", new MethodInfo.Parameter(Device.class, device),
                 new MethodInfo.Parameter(int.class, type));