diff --git a/main.js b/main.js
index fad6344..fa17332 100644
--- a/main.js
+++ b/main.js
@@ -5,6 +5,8 @@ const { SensorController } = require('./src/business/sensor-controller')
 const { UsbSerialBridge } = require('./src/business/usb-serial-bridge')
 const pkg = require('./package.json')
 
+if (require('electron-squirrel-startup')) app.quit()
+
 const cacheDir = app.getPath('userData')
 const cacheFile = path.join(cacheDir, 'app-cache.json')
 const fileRoot = path.join(cacheDir, 'files')
diff --git a/preload.js b/preload.js
index 876cbc5..f4b1ac1 100644
--- a/preload.js
+++ b/preload.js
@@ -10,6 +10,7 @@
 const { contextBridge, ipcRenderer } = require('electron')
 const nodeNet = require('net')
 const dns = require('dns')
+const { execFile } = require('child_process')
 
 function tryConnect(host, port, timeout) {
   return new Promise((resolve) => {
@@ -22,17 +23,41 @@ function tryConnect(host, port, timeout) {
   })
 }
 
+function normalizePingHost(input) {
+  const raw = String(input || '').trim()
+  if (!raw) return ''
+  try {
+    return new URL(raw).hostname
+  } catch {}
+  return raw.replace(/^https?:\/\//i, '').split('/')[0].split(':')[0]
+}
+
+function trySystemPing(host, timeout) {
+  return new Promise((resolve) => {
+    const wait = Math.max(1000, Number(timeout) || 2000)
+    execFile('ping', ['-n', '1', '-w', String(wait), host], { windowsHide: true }, (err) => {
+      resolve(!err)
+    })
+  })
+}
+
 const net = {
   async ping(host, timeout) {
+    const target = normalizePingHost(host)
+    if (!target) return false
+    const wait = Math.max(1000, Number(timeout) || 2000)
+    const isIp = nodeNet.isIP(target) !== 0
+
     try {
-      await dns.promises.resolve(host)
+      if (!isIp) await dns.promises.lookup(target)
     } catch {
-      return false
+      if (!await trySystemPing(target, wait)) return false
     }
-    for (const port of [443, 80]) {
-      if (await tryConnect(host, port, timeout)) return true
+
+    for (const port of [443, 80, 53]) {
+      if (await tryConnect(target, port, wait)) return true
     }
-    return false
+    return trySystemPing(target, wait)
   }
 }