diff --git a/common/buf/copy.go b/common/buf/copy.go
index 4cc3be88..72ee3ed8 100644
--- a/common/buf/copy.go
+++ b/common/buf/copy.go
@@ -56,6 +56,10 @@ type readError struct {
 	error
 }
 
+func NewReadError(err error) error {
+	return readError{err}
+}
+
 func (e readError) Error() string {
 	return e.error.Error()
 }
@@ -74,6 +78,10 @@ type writeError struct {
 	error
 }
 
+func NewWriteError(err error) error {
+	return writeError{err}
+}
+
 func (e writeError) Error() string {
 	return e.error.Error()
 }
diff --git a/common/mux/client.go b/common/mux/client.go
index 28380331..47943a2b 100644
--- a/common/mux/client.go
+++ b/common/mux/client.go
@@ -332,14 +332,14 @@ func (m *ClientWorker) Dispatch(ctx context.Context, link *transport.Link) bool
 
 func (m *ClientWorker) handleStatueKeepAlive(meta *FrameMetadata, reader *buf.BufferedReader) error {
 	if meta.Option.Has(OptionData) {
-		return buf.Copy(NewStreamReader(reader), buf.Discard)
+		return CopyChunk(reader, buf.Discard)
 	}
 	return nil
 }
 
 func (m *ClientWorker) handleStatusNew(meta *FrameMetadata, reader *buf.BufferedReader) error {
 	if meta.Option.Has(OptionData) {
-		return buf.Copy(NewStreamReader(reader), buf.Discard)
+		return CopyChunk(reader, buf.Discard)
 	}
 	return nil
 }
@@ -355,7 +355,19 @@ func (m *ClientWorker) handleStatusKeep(meta *FrameMetadata, reader *buf.Buffere
 		closingWriter := NewResponseWriter(meta.SessionID, m.link.Writer, protocol.TransferTypeStream)
 		closingWriter.Close()
 
-		return buf.Copy(NewStreamReader(reader), buf.Discard)
+		return CopyChunk(reader, buf.Discard)
+	}
+
+	if s.transferType == protocol.TransferTypeStream {
+		err := CopyChunk(reader, s.output)
+		if err != nil && buf.IsWriteError(err) {
+			errors.LogInfoInner(context.Background(), err, "failed to write to downstream. closing session ", s.ID)
+			s.Close(false)
+			// down stream can have a write err but don't return the err to terminate the whole mux connection
+			// because it's still available for other sessions
+			return nil
+		}
+		return err
 	}
 
 	rr := s.NewReader(reader, &meta.Target)
@@ -374,7 +386,7 @@ func (m *ClientWorker) handleStatusEnd(meta *FrameMetadata, reader *buf.Buffered
 		s.Close(false)
 	}
 	if meta.Option.Has(OptionData) {
-		return buf.Copy(NewStreamReader(reader), buf.Discard)
+		return CopyChunk(reader, buf.Discard)
 	}
 	return nil
 }
diff --git a/common/mux/reader.go b/common/mux/reader.go
index b9714cdf..d27a4f21 100644
--- a/common/mux/reader.go
+++ b/common/mux/reader.go
@@ -57,3 +57,32 @@ func (r *PacketReader) ReadMultiBuffer() (buf.MultiBuffer, error) {
 func NewStreamReader(reader *buf.BufferedReader) buf.Reader {
 	return crypto.NewChunkStreamReaderWithChunkCount(crypto.PlainChunkSizeParser{}, reader, 1)
 }
+
+func CopyChunk(reader *buf.BufferedReader, writer buf.Writer) error {
+	size, err := serial.ReadUint16(reader)
+	if err != nil {
+		return err
+	}
+	var writeErr error
+	for size > 0 {
+		mb, readErr := reader.ReadAtMost(int32(size))
+		if !mb.IsEmpty() {
+			size -= uint16(mb.Len())
+			if writeErr == nil {
+				if err := writer.WriteMultiBuffer(mb); err != nil {
+					writeErr = err
+				}
+			} else {
+				buf.ReleaseMulti(mb)
+			}
+			continue
+		}
+		if readErr != nil {
+			return buf.NewReadError(readErr)
+		}
+	}
+	if writeErr != nil {
+		return buf.NewWriteError(writeErr)
+	}
+	return nil
+}
diff --git a/common/mux/server.go b/common/mux/server.go
index d1cdac11..87aaf451 100644
--- a/common/mux/server.go
+++ b/common/mux/server.go
@@ -157,7 +157,7 @@ func (w *ServerWorker) Close() error {
 
 func (w *ServerWorker) handleStatusKeepAlive(meta *FrameMetadata, reader *buf.BufferedReader) error {
 	if meta.Option.Has(OptionData) {
-		return buf.Copy(NewStreamReader(reader), buf.Discard)
+		return CopyChunk(reader, buf.Discard)
 	}
 	return nil
 }
@@ -264,7 +264,7 @@ func (w *ServerWorker) handleStatusNew(ctx context.Context, meta *FrameMetadata,
 	link, err := w.dispatcher.Dispatch(ctx, meta.Target)
 	if err != nil {
 		if meta.Option.Has(OptionData) {
-			buf.Copy(NewStreamReader(reader), buf.Discard)
+			CopyChunk(reader, buf.Discard)
 		}
 		return errors.New("failed to dispatch request.").Base(err)
 	}
@@ -287,6 +287,15 @@ func (w *ServerWorker) handleStatusNew(ctx context.Context, meta *FrameMetadata,
 		return nil
 	}
 
+	if s.transferType == protocol.TransferTypeStream {
+		err = CopyChunk(reader, s.output)
+		if err != nil && buf.IsWriteError(err) {
+			s.Close(false)
+			return err
+		}
+		return err
+	}
+
 	rr := s.NewReader(reader, &meta.Target)
 	err = buf.Copy(rr, s.output)
 
@@ -308,7 +317,19 @@ func (w *ServerWorker) handleStatusKeep(meta *FrameMetadata, reader *buf.Buffere
 		closingWriter := NewResponseWriter(meta.SessionID, w.link.Writer, protocol.TransferTypeStream)
 		closingWriter.Close()
 
-		return buf.Copy(NewStreamReader(reader), buf.Discard)
+		return CopyChunk(reader, buf.Discard)
+	}
+
+	if s.transferType == protocol.TransferTypeStream {
+		err := CopyChunk(reader, s.output)
+		if err != nil && buf.IsWriteError(err) {
+			errors.LogInfoInner(context.Background(), err, "failed to write to downstream writer. closing session ", s.ID)
+			s.Close(false)
+			// down stream can have a write err but don't return the err to terminate the whole mux connection
+			// because it's still available for other sessions
+			return nil
+		}
+		return err
 	}
 
 	rr := s.NewReader(reader, &meta.Target)
@@ -328,7 +349,7 @@ func (w *ServerWorker) handleStatusEnd(meta *FrameMetadata, reader *buf.Buffered
 		s.Close(false)
 	}
 	if meta.Option.Has(OptionData) {
-		return buf.Copy(NewStreamReader(reader), buf.Discard)
+		return CopyChunk(reader, buf.Discard)
 	}
 	return nil
 }