diff --git a/v2rayN/ServiceLib/Global.cs b/v2rayN/ServiceLib/Global.cs
index dbf8ed86..48df5d22 100644
--- a/v2rayN/ServiceLib/Global.cs
+++ b/v2rayN/ServiceLib/Global.cs
@@ -429,12 +429,12 @@ namespace ServiceLib
             "fakedns+others"
         ];
 
-        public static readonly List<string> TunMtus =
+        public static readonly List<int> TunMtus =
         [
-            "1280",
-            "1408",
-            "1500",
-            "9000"
+            1280,
+            1408,
+            1500,
+            9000
         ];
 
         public static readonly List<string> TunStacks =
diff --git a/v2rayN/ServiceLib/Handler/ConfigHandler.cs b/v2rayN/ServiceLib/Handler/ConfigHandler.cs
index 03f16d48..4232496e 100644
--- a/v2rayN/ServiceLib/Handler/ConfigHandler.cs
+++ b/v2rayN/ServiceLib/Handler/ConfigHandler.cs
@@ -725,7 +725,7 @@ namespace ServiceLib.Handler
             profileItem.Network = string.Empty;
             if (profileItem.ShortId.IsNullOrEmpty())
             {
-                profileItem.ShortId = Global.TunMtus.FirstOrDefault();
+                profileItem.ShortId = Global.TunMtus.First().ToString();
             }
 
             if (profileItem.Id.IsNullOrEmpty())
diff --git a/v2rayN/ServiceLib/Services/CoreConfig/CoreConfigSingboxService.cs b/v2rayN/ServiceLib/Services/CoreConfig/CoreConfigSingboxService.cs
index 1ad3de13..5afae7d9 100644
--- a/v2rayN/ServiceLib/Services/CoreConfig/CoreConfigSingboxService.cs
+++ b/v2rayN/ServiceLib/Services/CoreConfig/CoreConfigSingboxService.cs
@@ -599,7 +599,7 @@ namespace ServiceLib.Services.CoreConfig
                 {
                     if (_config.TunModeItem.Mtu <= 0)
                     {
-                        _config.TunModeItem.Mtu = Utils.ToInt(Global.TunMtus.First());
+                        _config.TunModeItem.Mtu = Global.TunMtus.First();
                     }
                     if (Utils.IsNullOrEmpty(_config.TunModeItem.Stack))
                     {
@@ -745,7 +745,7 @@ namespace ServiceLib.Services.CoreConfig
                             outbound.peer_public_key = node.PublicKey;
                             outbound.reserved = Utils.String2List(node.Path)?.Select(int.Parse).ToList();
                             outbound.local_address = Utils.String2List(node.RequestHost);
-                            outbound.mtu = Utils.ToInt(node.ShortId.IsNullOrEmpty() ? Global.TunMtus.FirstOrDefault() : node.ShortId);
+                            outbound.mtu = Utils.ToInt(node.ShortId.IsNullOrEmpty() ? Global.TunMtus.First() : node.ShortId);
                             break;
                         }
                 }