From 39bf31bd56410802ded15483ec143d31408ccd46 Mon Sep 17 00:00:00 2001
From: MHSanaei <ho3ein.sanaei@gmail.com>
Date: Thu, 7 May 2026 19:50:47 +0200
Subject: [PATCH] fix(tun): use single mtu number per Xray spec

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
---
 web/assets/js/model/inbound.js  | 25 ++++++-------------------
 web/html/form/protocol/tun.html |  7 ++-----
 2 files changed, 8 insertions(+), 24 deletions(-)

diff --git a/web/assets/js/model/inbound.js b/web/assets/js/model/inbound.js
index a7c34f07..62deaf06 100644
--- a/web/assets/js/model/inbound.js
+++ b/web/assets/js/model/inbound.js
@@ -3197,7 +3197,7 @@ Inbound.TunSettings = class extends Inbound.Settings {
     constructor(
         protocol,
         name = 'xray0',
-        mtu = [1500, 1280],
+        mtu = 1500,
         gateway = [],
         dns = [],
         userLevel = 0,
@@ -3206,7 +3206,7 @@ Inbound.TunSettings = class extends Inbound.Settings {
     ) {
         super(protocol);
         this.name = name;
-        this.mtu = this._normalizeMtu(mtu);
+        this.mtu = Number(mtu) || 1500;
         this.gateway = Array.isArray(gateway) ? gateway : [];
         this.dns = Array.isArray(dns) ? dns : [];
         this.userLevel = userLevel;
@@ -3214,26 +3214,13 @@ Inbound.TunSettings = class extends Inbound.Settings {
         this.autoOutboundsInterface = autoOutboundsInterface;
     }
 
-    _normalizeMtu(mtu) {
-        if (!Array.isArray(mtu)) {
-            const single = Number(mtu) || 1500;
-            return [single, single];
-        }
-        if (mtu.length === 0) {
-            return [1500, 1280];
-        }
-        if (mtu.length === 1) {
-            const single = Number(mtu[0]) || 1500;
-            return [single, single];
-        }
-        return [Number(mtu[0]) || 1500, Number(mtu[1]) || 1280];
-    }
-
     static fromJson(json = {}) {
+        const rawMtu = json.mtu ?? json.MTU;
+        const mtu = Array.isArray(rawMtu) ? rawMtu[0] : rawMtu;
         return new Inbound.TunSettings(
             Protocols.TUN,
             json.name ?? 'xray0',
-            json.mtu ?? json.MTU ?? [1500, 1280],
+            mtu ?? 1500,
             json.gateway ?? json.Gateway ?? [],
             json.dns ?? json.DNS ?? [],
             json.userLevel ?? 0,
@@ -3245,7 +3232,7 @@ Inbound.TunSettings = class extends Inbound.Settings {
     toJson() {
         return {
             name: this.name || 'xray0',
-            mtu: this._normalizeMtu(this.mtu),
+            mtu: Number(this.mtu) || 1500,
             gateway: this.gateway,
             dns: this.dns,
             userLevel: this.userLevel || 0,
diff --git a/web/html/form/protocol/tun.html b/web/html/form/protocol/tun.html
index d1b95025..5541d327 100644
--- a/web/html/form/protocol/tun.html
+++ b/web/html/form/protocol/tun.html
@@ -18,14 +18,11 @@
         <template slot="title">
           <span>{{ i18n "pages.xray.tun.mtuDesc" }}</span>
         </template>
-        MTU IPv4
+        MTU
         <a-icon type="question-circle"></a-icon>
       </a-tooltip>
     </template>
-    <a-input-number v-model.number="inbound.settings.mtu[0]" :min="1" :max="9000" placeholder="1500"></a-input-number>
-  </a-form-item>
-  <a-form-item label="MTU IPv6">
-    <a-input-number v-model.number="inbound.settings.mtu[1]" :min="1" :max="9000" placeholder="1280"></a-input-number>
+    <a-input-number v-model.number="inbound.settings.mtu" :min="1" :max="9000" placeholder="1500"></a-input-number>
   </a-form-item>
   <a-form-item label="Gateway">
     <a-select mode="tags" v-model="inbound.settings.gateway" :style="{ width: '100%' }" :token-separators="[',']"