diff --git a/WebRTCController/app/src/main/java/com/ttstd/controller/webrtc/WebRtcClient.java b/WebRTCController/app/src/main/java/com/ttstd/controller/webrtc/WebRtcClient.java
index e224a4b..bf8c7cd 100644
--- a/WebRTCController/app/src/main/java/com/ttstd/controller/webrtc/WebRtcClient.java
+++ b/WebRTCController/app/src/main/java/com/ttstd/controller/webrtc/WebRtcClient.java
@@ -256,7 +256,7 @@ public class WebRtcClient {
     }
 
     public void sendControlCommand(ControlMessage message) {
-        if (dataChannel != null && dataChannel.state() == DataChannel.State.OPEN) {
+        if (isDataChannelOpen()) {
             DataChannel.Buffer buffer = new DataChannel.Buffer(
                     ByteBuffer.wrap(message.toByteArray()), false);
             dataChannel.send(buffer);
@@ -269,7 +269,7 @@ public class WebRtcClient {
      * fps <= 0 表示沿用当前帧率。
      */
     public void requestResolutionChange(int width, int height, int fps) {
-        if (dataChannel != null && dataChannel.state() == DataChannel.State.OPEN) {
+        if (isDataChannelOpen()) {
             ControlMessage msg = ControlMessage.newBuilder()
                     .setAction(Action.SET_RESOLUTION)
                     .setWidth(width)
@@ -283,21 +283,28 @@ public class WebRtcClient {
     public void close() {
         if (remoteVideoTrack != null && remoteSurfaceView != null) {
             remoteVideoTrack.removeSink(remoteSurfaceView);
+            remoteVideoTrack = null;
         }
         if (dataChannel != null) {
+            try { dataChannel.unregisterObserver(); } catch (Exception ignored) {}
             dataChannel.close();
             dataChannel.dispose();
+            dataChannel = null;
         }
         if (videoDataChannel != null) {
+            try { videoDataChannel.unregisterObserver(); } catch (Exception ignored) {}
             videoDataChannel.close();
             videoDataChannel.dispose();
+            videoDataChannel = null;
         }
         if (peerConnection != null) {
             peerConnection.close();
             peerConnection.dispose();
+            peerConnection = null;
         }
         if (peerConnectionFactory != null) {
             peerConnectionFactory.dispose();
+            peerConnectionFactory = null;
         }
     }
 
@@ -317,7 +324,12 @@ public class WebRtcClient {
 
             @Override
             public void onStateChange() {
-                Log.d(TAG, "DataChannel state: " + dc.state());
+                try {
+                    DataChannel.State state = dc.state();
+                    Log.d(TAG, "DataChannel state: " + state);
+                } catch (IllegalStateException e) {
+                    Log.w(TAG, "DataChannel state error (already disposed?)");
+                }
             }
 
             @Override
@@ -348,7 +360,12 @@ public class WebRtcClient {
 
             @Override
             public void onStateChange() {
-                Log.d(TAG, "Video DataChannel state: " + dc.state());
+                try {
+                    DataChannel.State state = dc.state();
+                    Log.d(TAG, "Video DataChannel state: " + state);
+                } catch (IllegalStateException e) {
+                    Log.w(TAG, "Video DataChannel state error (already disposed?)");
+                }
             }
 
             @Override
@@ -369,7 +386,13 @@ public class WebRtcClient {
     }
 
     public boolean isVideoDataChannelOpen() {
-        return videoDataChannel != null && videoDataChannel.state() == DataChannel.State.OPEN;
+        DataChannel dc = videoDataChannel;
+        if (dc == null) return false;
+        try {
+            return dc.state() == DataChannel.State.OPEN;
+        } catch (IllegalStateException e) {
+            return false;
+        }
     }
 
     /** 请求被控端切换屏幕串流模式（WebRTC / 自编码）。 */
@@ -423,6 +446,12 @@ public class WebRtcClient {
 
     /// 控制 DataChannel 是否已打开（用于状态显示）。
     public boolean isDataChannelOpen() {
-        return dataChannel != null && dataChannel.state() == DataChannel.State.OPEN;
+        DataChannel dc = dataChannel;
+        if (dc == null) return false;
+        try {
+            return dc.state() == DataChannel.State.OPEN;
+        } catch (IllegalStateException e) {
+            return false;
+        }
     }
 }