diff --git a/app/proxyman/outbound/handler.go b/app/proxyman/outbound/handler.go
index 4c3b16a12..91952fd1d 100644
--- a/app/proxyman/outbound/handler.go
+++ b/app/proxyman/outbound/handler.go
@@ -122,7 +122,10 @@ func NewHandler(ctx context.Context, config *core.OutboundHandlerConfig) (outbou
 			if config.Concurrency < 0 {
 				h.mux = &mux.ClientManager{Enabled: false}
 			}
-			if config.Concurrency >= 0 && config.Concurrency <= 128 {
+			if config.Concurrency == 0 {
+				config.Concurrency = 8 // same as before
+			}
+			if config.Concurrency > 0 && config.Concurrency < 128 && h.streamSettings != nil && h.streamSettings.ProtocolName == "xdrive" {
 				config.Concurrency = 128
 			}
 			if config.Concurrency > 0 {