diff --git a/GateWay-KeepAlive.ps1 b/GateWay-KeepAlive.ps1
index f547839..9ad5626 100644
--- a/GateWay-KeepAlive.ps1
+++ b/GateWay-KeepAlive.ps1
@@ -1,188 +1,263 @@
-# $Global:TestDomain = "www.google.com"               #测试代理是否可用
-# $Global:TestIP = "223.5.5.5"                        #测试是否连接网络
-# $Global:originalDns = "223.5.5.5"                   #默认DNS
-# $Global:originalGateway = "192.168.6.1"             #默认网关
-# $Global:CustomGateway = "192.168.6.2"               #代理网关
-# $Global:CustomIP = "192.168.6.4"                    #默认ip
-# $Global:TargetNetworkAdapter = {}                   #网络适配器实例
-# $Global:TargetNetworkAdapterKeyword = "Ethernet"    #网络适配器名字通配符
-# $Global:isCustomGateway = $false                    #是否为自定义网关
+. (Join-Path $PSScriptRoot 'config.ps1')
+. (Join-Path $PSScriptRoot 'logger.ps1')
+. (Join-Path $PSScriptRoot 'proxy-test.ps1')
 
-. $(-Join($(Get-Location).Path, '\config.ps1'))
-. $(-Join($(Get-Location).Path, '\proxy-test.ps1'))
-. $(-Join($(Get-Location).Path, '\logger.ps1'))
+$Script:ProxySuccessCount = 0
+$Script:ProxyFailureCount = 0
+$Script:LastSwitchTime = (Get-Date).AddSeconds(-1 * $Global:SwitchCooldownSeconds)
 
-
-function isDhcpEnable(){
-    return Get-NetIPConfiguration | select-object InterfaceAlias, IPv4Address, @{n="dhcp";e={$_.NetIPv4Interface.DHCP}} | Select-Object -ExpandProperty dhcp
+function Test-IsAdministrator {
+    $identity = [Security.Principal.WindowsIdentity]::GetCurrent()
+    $principal = [Security.Principal.WindowsPrincipal]$identity
+    return $principal.IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator)
 }
 
-function isForeignConnected {
-    # check foreign network availability
-    $result = Test-NetConnection -ComputerName $Global:TestDomain -Port 443
-
-    if ($result.TcpTestSucceeded) {
-        Write-Log -Message "Successfully connected to $($Global:TestDomain) via HTTPS. isCustomGateway:$($Global:isCustomGateway)"
-        return $true
-    } else {
-        Write-Log -Message "Failed to connect to $($Global:TestDomain) via HTTPS. isCustomGateway:$($Global:isCustomGateway)"
-        return $false
-    }  
+function Request-Administrator {
+    Write-Log -Message "Requesting Administrator privileges..."
+    Start-Process pwsh -ArgumentList "-NoExit", "-File", $PSCommandPath -Verb RunAs
+    exit
 }
 
-function isNetworkConnected {
-    # check network availability
-    $result = $(Test-Connection -ComputerName $Global:TestIP -Count 1).Status -eq 'Success'
-    if ($result) {
-        Write-Log -Message "Successfully connected to $($Global:TestIP) via ICMP. isCustomGateway:$($Global:isCustomGateway)"
-        return $true
-    } else {
-        Write-Log -Message "Failed to connect to $($Global:TestIP) via ICMP. isCustomGateway:$($Global:isCustomGateway)"
-        return $false
-    }  
-}
+function Get-TargetAdapter {
+    $adapter = Get-NetAdapter |
+        Where-Object { $_.Name.Contains($Global:TargetNetworkAdapterKeyword) -and $_.Status -eq "Up" } |
+        Select-Object -First 1
 
-function setDhcp($enable){
-    if($enable){
-        Set-NetIPInterface -InterfaceAlias $Global:TargetNetworkAdapter.name -Dhcp Enabled
-        Write-Log -Message "enable dhcp"
-    } else {
-        Set-NetIPInterface -InterfaceAlias $Global:TargetNetworkAdapter.name -Dhcp Disabled
-        Write-Log -Message "disable dhcp"
+    if (-not $adapter) {
+        throw "No active network adapter found by keyword '$($Global:TargetNetworkAdapterKeyword)'."
     }
+
+    $Global:TargetNetworkAdapter = $adapter
+    Write-Log -Message "Target adapter: $($adapter.Name), InterfaceIndex: $($adapter.ifIndex)"
+    return $adapter
 }
 
-function changeGateway{
+function Get-CurrentDefaultGateway {
     param(
-        $adapter,$isCustomGateway
+        [Parameter(Mandatory)]
+        [int]$InterfaceIndex
     )
-    Write-Log -Message "Changing gateway for adapter: $($adapter.Name) isCustomGateway $($isCustomGateway)"
-    
-  
-    # check gateway availability
-    if($isCustomGateway){
-        $currentGateway = $(Get-NetIPConfiguration).IPv4DefaultGateway.NextHop
-        if($currentGateway -eq $Global:CustomGateway){
-            Write-Log -Message "current gateway is $currentGateway same as targetGateway $Global:TargetGateway, change gateway canceled"
-            $Global:isCustomGateway = $true
-            return
-        }
-        $result = $(Test-Connection $Global:CustomGateway -Count 1).Status
-        if (! ($result -eq 'Success')){
-            Write-Log -Message "custom gateway $Global:CustomGateway is $result, refuse to change"
-            return
-        }
+
+    $route = Get-NetRoute -InterfaceIndex $InterfaceIndex -DestinationPrefix "0.0.0.0/0" -ErrorAction SilentlyContinue |
+        Sort-Object RouteMetric, ifMetric |
+        Select-Object -First 1
+
+    if ($route) {
+        return $route.NextHop
     }
 
-    # check current ip configuration
-    $existingIP = Get-NetIPAddress -InterfaceAlias $adapter.Name -AddressFamily IPv4
+    return $null
+}
 
-    # if have ip configuration, delete it
-    if ($existingIP) {
-        Write-Log -Message "Removing existing IP address: $($existingIP.IPAddress)"
-        Remove-NetIPAddress -InterfaceAlias $adapter.Name -Confirm:$false
+function Get-CurrentMode {
+    param(
+        [Parameter(Mandatory)]
+        [int]$InterfaceIndex
+    )
+
+    $gateway = Get-CurrentDefaultGateway -InterfaceIndex $InterfaceIndex
+    if ($gateway -eq $Global:CustomGateway) {
+        return "PROXY"
     }
 
-    # delete current route(gateway)
-    $existingRoute = Get-NetRoute -InterfaceAlias $adapter.Name -DestinationPrefix "0.0.0.0/0"
-    if ($existingRoute) {
-        Write-Log -Message "Removing existing default route..."
-        Remove-NetRoute -InterfaceAlias $adapter.Name  -Confirm:$false
+    return "DIRECT"
+}
+
+function Test-CooldownExpired {
+    $elapsed = ((Get-Date) - $Script:LastSwitchTime).TotalSeconds
+    return $elapsed -ge $Global:SwitchCooldownSeconds
+}
+
+function Test-HostReachable {
+    param(
+        [Parameter(Mandatory)]
+        [string]$Host
+    )
+
+    try {
+        return [bool](Test-Connection -ComputerName $Host -Count 1 -Quiet -ErrorAction Stop)
+    } catch {
+        Write-Log -Message "Host check failed for ${Host}: $_"
+        return $false
+    }
+}
+
+function Test-ProxyDns {
+    try {
+        $result = Resolve-DnsName -Name $Global:TestDomain -Server $Global:CustomGateway -ErrorAction Stop
+        return [bool]$result
+    } catch {
+        Write-Log -Message "Proxy DNS check failed via $($Global:CustomGateway): $_"
+        return $false
+    }
+}
+
+function Test-InternetTcp {
+    try {
+        return [bool](Test-NetConnection -ComputerName $Global:TestDomain -Port 443 -InformationLevel Quiet)
+    } catch {
+        Write-Log -Message "Internet TCP check failed for $($Global:TestDomain):443: $_"
+        return $false
+    }
+}
+
+function Test-ProxyHealthy {
+    $gatewayReachable = Test-HostReachable -Host $Global:CustomGateway
+    if (-not $gatewayReachable) {
+        Write-Log -Message "Proxy gateway $($Global:CustomGateway) is not reachable."
+        return $false
     }
 
-    if ($isCustomGateway){ #setting gateway
+    $dnsOk = Test-ProxyDns
+    if (-not $dnsOk) {
+        return $false
+    }
 
-        # config customGateway
-        $Global:isCustomGateway = $true
+    if ($Global:UseSocksProxyHealthCheck) {
+        return Test-SocksProxy -ProxyHost $Global:CustomGateway -ProxyPort $Global:ProxyPort -TestHost $Global:TestDomain -TestPort 443
+    }
 
-        # setting dns server
-        Set-DnsClientServerAddress -InterfaceAlias $adapter.name -ServerAddresses ($Global:CustomGateway, $Global:CustomGateway)
-        # disable dhcp
-        setDhcp($false)
-        # setting gateway to customGateway
-        New-NetIPAddress -InterfaceAlias $adapter.Name -AddressFamily IPv4 -IPAddress $Global:CustomIP -PrefixLength 24 -DefaultGateway $Global:CustomGateway
+    return $true
+}
+
+function Set-DefaultGateway {
+    param(
+        [Parameter(Mandatory)]
+        [int]$InterfaceIndex,
+
+        [Parameter(Mandatory)]
+        [string]$Gateway
+    )
+
+    $currentGateway = Get-CurrentDefaultGateway -InterfaceIndex $InterfaceIndex
+    if ($currentGateway -eq $Gateway) {
+        Write-Log -Message "Default gateway is already $Gateway."
+        return
+    }
+
+    $existingRoutes = Get-NetRoute -InterfaceIndex $InterfaceIndex -DestinationPrefix "0.0.0.0/0" -ErrorAction SilentlyContinue
+    foreach ($route in $existingRoutes) {
+        Write-Log -Message "Removing default route $($route.NextHop) from interface $InterfaceIndex."
+        Remove-NetRoute -InterfaceIndex $InterfaceIndex -DestinationPrefix "0.0.0.0/0" -NextHop $route.NextHop -Confirm:$false
+    }
+
+    Write-Log -Message "Adding default route $Gateway to interface $InterfaceIndex."
+    New-NetRoute -InterfaceIndex $InterfaceIndex -DestinationPrefix "0.0.0.0/0" -NextHop $Gateway -RouteMetric 1 | Out-Null
+}
+
+function Set-ProxyDns {
+    param(
+        [Parameter(Mandatory)]
+        [int]$InterfaceIndex
+    )
+
+    Write-Log -Message "Setting DNS to proxy gateway $($Global:CustomGateway)."
+    Set-DnsClientServerAddress -InterfaceIndex $InterfaceIndex -ServerAddresses $Global:CustomGateway
+    Clear-DnsClientCache
+}
+
+function Set-DirectDns {
+    param(
+        [Parameter(Mandatory)]
+        [int]$InterfaceIndex
+    )
+
+    if ($Global:DirectDnsServers -and $Global:DirectDnsServers.Count -gt 0) {
+        Write-Log -Message "Setting DNS to $($Global:DirectDnsServers -join ', ')."
+        Set-DnsClientServerAddress -InterfaceIndex $InterfaceIndex -ServerAddresses $Global:DirectDnsServers
     } else {
-        # config originalGateway
-        $Global:isCustomGateway = $false
-
-        # setting dns server
-        Set-DnsClientServerAddress -InterfaceAlias $adapter.name -ServerAddresses ($Global:originalDns, $Global:originalDns)
-        # disable dhcp
-        setDhcp($false)
-        # setting gateway to originalGateway
-        New-NetIPAddress -InterfaceAlias $adapter.Name -AddressFamily IPv4 -IPAddress $Global:CustomIP -PrefixLength 24 -DefaultGateway $Global:originalGateway
+        Write-Log -Message "Resetting DNS to DHCP provided servers."
+        Set-DnsClientServerAddress -InterfaceIndex $InterfaceIndex -ResetServerAddresses
     }
-    Start-Sleep 3
+
+    Clear-DnsClientCache
 }
 
+function Switch-ToProxy {
+    param(
+        [Parameter(Mandatory)]
+        [int]$InterfaceIndex
+    )
 
-function getIPAddress(){
-    $IP = Get-NetIPConfiguration | Select-Object -ExpandProperty IPV4Address | Select-Object -ExpandProperty IPAddress
-    return $IP
+    Write-Log -Message "Switching to proxy gateway $($Global:CustomGateway)." -ToEventLog
+    Set-ProxyDns -InterfaceIndex $InterfaceIndex
+    Set-DefaultGateway -InterfaceIndex $InterfaceIndex -Gateway $Global:CustomGateway
+    $Global:isCustomGateway = $true
+    $Script:LastSwitchTime = Get-Date
 }
 
-function getNetworkAdapter(){
-    $networkAdapters = Get-NetAdapter | ForEach-Object {
-        [PSCustomObject]@{
-            Name       = $_.Name
-            Interface  = $_.InterfaceDescription
-            Status     = $_.Status
-            LinkSpeed  = $_.LinkSpeed
-            MacAddress = $_.MacAddress
-        }
-    }
-    
-    foreach ($networkAdapter in $networkAdapters){
-        if($networkAdapter.name.Contains($TargetNetworkAdapterKeyword)){
-            $Global:TargetNetworkAdapter = $networkAdapter
-            break;
-        }
-    }
-    Write-Log -Message "getNetworkAdapter: $Global:TargetNetworkAdapter"
+function Switch-ToDirect {
+    param(
+        [Parameter(Mandatory)]
+        [int]$InterfaceIndex
+    )
+
+    Write-Log -Message "Switching to direct gateway $($Global:originalGateway)." -ToEventLog
+    Set-DefaultGateway -InterfaceIndex $InterfaceIndex -Gateway $Global:originalGateway
+    Set-DirectDns -InterfaceIndex $InterfaceIndex
+    $Global:isCustomGateway = $false
+    $Script:LastSwitchTime = Get-Date
 }
 
-function init {
+function Initialize-GatewayKeepAlive {
+    if (-not (Test-IsAdministrator)) {
+        Request-Administrator
+    }
+
     Write-Log -Message "GateWay-KeepAliveForPowershell is start" -ToEventLog
-    # check permission
-    $IsAdmin = [Security.Principal.WindowsPrincipal][Security.Principal.WindowsIdentity]::GetCurrent()
-    if (-not $IsAdmin.IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator)) {
-        # if not admin permission, restart it with admin permission
-        Write-Log -Message "Requesting Administrator privileges..."
-        Start-Process pwsh -ArgumentList "-NoExit", "-File", $PSCommandPath -Verb RunAs
-        exit
-    }
+    Write-Log -Message "Running with Administrator privileges."
 
-    Write-Log -Message "Running with Administrator privileges!"
+    $adapter = Get-TargetAdapter
+    $mode = Get-CurrentMode -InterfaceIndex $adapter.ifIndex
+    $Global:isCustomGateway = $mode -eq "PROXY"
+    Write-Log -Message "Initial mode: $mode"
 
-    # get netAdapter instance
-    getNetworkAdapter
-
-    Write-Log -Message "current adapter: $($Global:TargetNetworkAdapter.name)"
-
-    # try to change to customGateway at start
-    changeGateway $Global:TargetNetworkAdapter $true
+    return $adapter
 }
 
-function loop(){
-    while($true){
-        # if network offline and using customGateway, try to restore to originalGateway
-        if((!$(isNetworkConnected)) -and $Global:isCustomGateway){
-            Write-Log -Message "Network is down, change to original gateway" -ToEventLog
-            changeGateway $Global:TargetNetworkAdapter $false
-        } 
+function Start-GatewayKeepAliveLoop {
+    param(
+        [Parameter(Mandatory)]
+        $Adapter
+    )
 
-        # if customGateway proxy is working and using original gateway, try to change to customGateway
-        if($(Test-SocksProxy -ProxyHost $Global:CustomGateway -ProxyPort 1070) -and (!$Global:isCustomGateway)){
-            Write-Log -Message "isCustomGateway $Global:isCustomGateway"
-            Write-Log -Message "proxy host is up, change to custom gateway" -ToEventLog
-            changeGateway $Global:TargetNetworkAdapter $true
+    while ($true) {
+        $mode = Get-CurrentMode -InterfaceIndex $Adapter.ifIndex
+        $Global:isCustomGateway = $mode -eq "PROXY"
+        $proxyHealthy = Test-ProxyHealthy
+
+        if ($mode -eq "PROXY") {
+            $internetOk = Test-InternetTcp
+            if ($proxyHealthy -and $internetOk) {
+                $Script:ProxyFailureCount = 0
+            } else {
+                $Script:ProxyFailureCount++
+                Write-Log -Message "Proxy mode health failed $($Script:ProxyFailureCount)/$($Global:ProxyFailureThreshold)."
+            }
+
+            if ($Script:ProxyFailureCount -ge $Global:ProxyFailureThreshold -and (Test-CooldownExpired)) {
+                Switch-ToDirect -InterfaceIndex $Adapter.ifIndex
+                $Script:ProxyFailureCount = 0
+                $Script:ProxySuccessCount = 0
+            }
+        } else {
+            if ($proxyHealthy) {
+                $Script:ProxySuccessCount++
+                Write-Log -Message "Proxy mode candidate succeeded $($Script:ProxySuccessCount)/$($Global:ProxySuccessThreshold)."
+            } else {
+                $Script:ProxySuccessCount = 0
+            }
+
+            if ($Script:ProxySuccessCount -ge $Global:ProxySuccessThreshold -and (Test-CooldownExpired)) {
+                Switch-ToProxy -InterfaceIndex $Adapter.ifIndex
+                $Script:ProxySuccessCount = 0
+                $Script:ProxyFailureCount = 0
+            }
         }
 
-        # if customGateway proxy is not working but network still online, do nothing
-
-        Start-Sleep 1
+        Start-Sleep -Seconds $Global:HealthCheckIntervalSeconds
     }
 }
 
-init
-loop
+$adapter = Initialize-GatewayKeepAlive
+Start-GatewayKeepAliveLoop -Adapter $adapter
diff --git a/config.ps1 b/config.ps1
index 2f1a47a..dfa272d 100644
--- a/config.ps1
+++ b/config.ps1
@@ -3,8 +3,15 @@ $Global:TestIP = "223.5.5.5"                        #测试是否连接网络
 $Global:originalDns = "223.5.5.5"                   #默认DNS
 $Global:originalGateway = "192.168.6.1"             #默认网关
 $Global:CustomGateway = "192.168.6.2"               #代理网关
-$Global:CustomIP = "192.168.6.4"                    #默认ip
 $Global:TargetNetworkAdapter = {}                   #网络适配器实例
 $Global:TargetNetworkAdapterKeyword = "Ethernet"    #网络适配器名字通配符
 $Global:isCustomGateway = $false                    #是否为自定义网关
-$Global:isDebugging = $false                         #是否为调试模式（日志输出到控制台）
\ No newline at end of file
+$Global:isDebugging = $false                        #是否为调试模式（日志输出到控制台）
+
+$Global:ProxyPort = 1070                            #代理网关SOCKS5检测端口
+$Global:UseSocksProxyHealthCheck = $true            #是否检测SOCKS5代理端口
+$Global:DirectDnsServers = @()                      #直连模式DNS，留空表示恢复DHCP下发的DNS
+$Global:ProxySuccessThreshold = 3                   #连续成功多少次后切换到代理网关
+$Global:ProxyFailureThreshold = 3                   #连续失败多少次后切回默认网关
+$Global:HealthCheckIntervalSeconds = 5              #检测间隔
+$Global:SwitchCooldownSeconds = 30                  #切换后的冷却时间
diff --git a/logger.ps1 b/logger.ps1
index 666e175..763e42c 100644
--- a/logger.ps1
+++ b/logger.ps1
@@ -1,4 +1,4 @@
-. $(-Join($(Get-Location).Path, '\config.ps1'))
+. (Join-Path $PSScriptRoot 'config.ps1')
 
 function Write-Log {
     param (
diff --git a/proxy-test.ps1 b/proxy-test.ps1
index c853bc3..a4fe40a 100644
--- a/proxy-test.ps1
+++ b/proxy-test.ps1
@@ -1,12 +1,13 @@
-. $(-Join($(Get-Location).Path, '\logger.ps1'))
-. $(-Join($(Get-Location).Path, '\config.ps1'))
+. (Join-Path $PSScriptRoot 'config.ps1')
+. (Join-Path $PSScriptRoot 'logger.ps1')
 
 function Test-SocksProxy {
     param (
         [string]$ProxyHost,
         [int]$ProxyPort,
         [string]$TestHost = "google.com",
-        [int]$TestPort = 443
+        [int]$TestPort = 443,
+        [int]$TimeoutMilliseconds = 1500
     )
 
     $result = $false
@@ -22,7 +23,10 @@ function Test-SocksProxy {
         $tcpClient = New-Object System.Net.Sockets.TcpClient
         $tcpClient.SendTimeout = 1000
         $tcpClient.ReceiveTimeout = 1000
-        $tcpClient.Connect($ProxyHost, $ProxyPort)
+        $connectTask = $tcpClient.ConnectAsync($ProxyHost, $ProxyPort)
+        if (-not $connectTask.Wait($TimeoutMilliseconds)) {
+            throw "Timed out connecting to ${ProxyHost}:$ProxyPort."
+        }
 
         # 代理成功连接，开始验证目标地址是否可达
         $stream = $tcpClient.GetStream()
@@ -33,7 +37,10 @@ function Test-SocksProxy {
 
         # 接收服务器响应
         $response = New-Object byte[] 2
-        $stream.Read($response, 0, $response.Length)
+        $bytesRead = $stream.Read($response, 0, $response.Length)
+        if ($bytesRead -lt $response.Length) {
+            throw "SOCKS handshake response is incomplete."
+        }
 
         if ($response[1] -ne 0x00) {
             throw "SOCKS handshake failed. Proxy does not support no-authentication."
@@ -55,7 +62,10 @@ function Test-SocksProxy {
 
         # 接收连接响应
         $connectResponse = New-Object byte[] 10
-        $stream.Read($connectResponse, 0, $connectResponse.Length)
+        $bytesRead = $stream.Read($connectResponse, 0, $connectResponse.Length)
+        if ($bytesRead -lt 2) {
+            throw "SOCKS connect response is incomplete."
+        }
 
         if ($connectResponse[1] -eq 0x00) {
             Write-Log -Message "Proxy is valid and can connect to ${TestHost}:$TestPort."