diff --git a/web/assets/js/model/inbound.js b/web/assets/js/model/inbound.js
index b196a06d8..ed72f8f63 100644
--- a/web/assets/js/model/inbound.js
+++ b/web/assets/js/model/inbound.js
@@ -324,7 +324,7 @@ class KcpStreamSettings extends XrayCommonClass {
         uplinkCapacity = 5,
         downlinkCapacity = 20,
         cwndMultiplier = 1,
-        maxSendingWindow = 0,
+        maxSendingWindow = 1350,
     ) {
         super();
         this.mtu = mtu;
diff --git a/web/assets/js/model/outbound.js b/web/assets/js/model/outbound.js
index 9b09ae7c0..2a288c499 100644
--- a/web/assets/js/model/outbound.js
+++ b/web/assets/js/model/outbound.js
@@ -170,7 +170,7 @@ class KcpStreamSettings extends CommonClass {
         uplinkCapacity = 5,
         downlinkCapacity = 20,
         cwndMultiplier = 1,
-        maxSendingWindow = 0,
+        maxSendingWindow = 1350,
     ) {
         super();
         this.mtu = mtu;