diff --git a/ostp-flutter/android/app/src/main/res/values/ic_launcher_background.xml b/ostp-flutter/android/app/src/main/res/values/ic_launcher_background.xml
new file mode 100644
index 0000000..ea9c223
--- /dev/null
+++ b/ostp-flutter/android/app/src/main/res/values/ic_launcher_background.xml
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+  <color name="ic_launcher_background">#fff</color>
+</resources>
\ No newline at end of file
diff --git a/ostp-gui/src/index.html b/ostp-gui/src/index.html
index 808a3e1..6175df9 100644
--- a/ostp-gui/src/index.html
+++ b/ostp-gui/src/index.html
@@ -257,13 +257,6 @@
             </label>
           </div>
 
-          <div class="field-group" id="group-tun-stack">
-            <label class="field-label" for="in-tun-stack" data-i18n="label_tun_stack">TUN Stack</label>
-            <select id="in-tun-stack" class="field-input">
-              <option value="system">System (tun2socks)</option>
-              <option value="ostp">OSTP (Native)</option>
-            </select>
-          </div>
 
           <div class="toggle-row">
             <div class="toggle-text">
diff --git a/ostp-gui/src/main.js b/ostp-gui/src/main.js
index 70c409c..21be5bc 100644
--- a/ostp-gui/src/main.js
+++ b/ostp-gui/src/main.js
@@ -51,8 +51,6 @@ const inPbk          = $('in-pbk');
 const inSid          = $('in-sid');
 const inMtu          = $('in-mtu');
 const inTun          = $('in-tun-mode');
-const inTunStack     = $('in-tun-stack');
-const groupTunStack  = $('group-tun-stack');
 const inMux          = $('in-mux-mode');
 const inMuxSessions  = $('in-mux-sessions');
 const inDebug        = $('in-debug');
@@ -245,13 +243,10 @@ async function loadConfigIntoForm() {
     inPbk.value     = c.reality?.pbk           || '';
     inSid.value     = c.reality?.sid           || '';
     inMtu.value     = c.mtu           || '';
-    inTun.checked   = !!c.tun?.enable;
-    inTunStack.value = c.tun?.stack   || 'system';
+    inTun.checked   = !!c.tun?.enabled;
     inMux.checked   = !!c.mux?.enabled;
     inMuxSessions.value = c.mux?.sessions || '';
     
-    groupTunStack.style.display = inTun.checked ? 'block' : 'none';
-
     // owndns: detect if saved dns is 10.1.0.1
     const savedDns = c.tun?.dns || '';
     const isOwndns = savedDns === '10.1.0.1';
@@ -322,13 +317,11 @@ async function handleSave(silent = false) {
     delete rawConfig.mux;
   }
 
-  if (!rawConfig.tun) {
-    rawConfig.tun = { wintun_path: './wintun.dll', ipv4_address: '10.1.0.2/24' };
-  }
+  rawConfig.tun = rawConfig.tun || {};
   rawConfig.tun.enable = inTun.checked;
+  rawConfig.tun.stack = 'ostp';
   // owndns: if toggle is on, always write 10.1.0.1; otherwise use the custom field
   rawConfig.tun.dns    = inOwndns.checked ? '10.1.0.1' : (inDns.value.trim() || null);
-  rawConfig.tun.stack  = inTunStack.value;
 
   rawConfig.exclude = {
     domains:   splitLines(inDomains.value),
@@ -479,7 +472,6 @@ window.addEventListener('DOMContentLoaded', async () => {
     updateDnsVisibility();
     scheduleAutoSave();
   });
-  inTun.addEventListener('change', () => { groupTunStack.style.display = inTun.checked ? 'block' : 'none'; });
   importInput.addEventListener('keydown', e => { if (e.key === 'Enter') handleImport(); });
 
   // Auto-save wiring