diff --git a/hosts/xlab-gateway/networking.nix b/hosts/xlab-gateway/networking.nix
index 8a8af86..3aad638 100644
--- a/hosts/xlab-gateway/networking.nix
+++ b/hosts/xlab-gateway/networking.nix
@@ -77,7 +77,8 @@
             
             # 终极修复：使用位掩码 & (syn) == syn，同时捕获 SYN 和 SYN-ACK。
             # 无论数据包是进 WG 还是出 WG，都会根据出口路由(rt mtu)自动调整 MSS。
-            tcp flags & (syn) == syn tcp option maxseg size set rt mtu
+            #tcp flags & (syn) == syn tcp option maxseg size set rt mtu
+            tcp flags & (syn|ack) == syn tcp option maxseg size set 1280
           }
           chain postrouting {
             type filter hook postrouting priority filter; policy accept;