diff --git a/v2rayN/ServiceLib/Common/DownloaderHelper.cs b/v2rayN/ServiceLib/Common/DownloaderHelper.cs
index fe468566..2aaa2371 100644
--- a/v2rayN/ServiceLib/Common/DownloaderHelper.cs
+++ b/v2rayN/ServiceLib/Common/DownloaderHelper.cs
@@ -36,7 +36,7 @@ namespace ServiceLib.Common
                 }
             };
 
-            using var downloader = new Downloader.DownloadService(downloadOpt);
+            await using var downloader = new Downloader.DownloadService(downloadOpt);
             downloader.DownloadFileCompleted += (sender, value) =>
             {
                 if (value.Error != null)
@@ -46,12 +46,12 @@ namespace ServiceLib.Common
             };
 
             using var cts = new CancellationTokenSource();
-            using var stream = await downloader.DownloadFileTaskAsync(address: url, cts.Token).WaitAsync(TimeSpan.FromSeconds(timeout), cts.Token);
+            await using var stream = await downloader.DownloadFileTaskAsync(address: url, cts.Token).WaitAsync(TimeSpan.FromSeconds(timeout), cts.Token);
             using StreamReader reader = new(stream);
 
             downloadOpt = null;
 
-            return reader.ReadToEnd();
+            return await reader.ReadToEndAsync(cts.Token);
         }
 
         public async Task DownloadDataAsync4Speed(IWebProxy webProxy, string url, IProgress<string> progress, int timeout)
@@ -72,11 +72,11 @@ namespace ServiceLib.Common
                 }
             };
 
-            DateTime totalDatetime = DateTime.Now;
-            int totalSecond = 0;
+            var totalDatetime = DateTime.Now;
+            var totalSecond = 0;
             var hasValue = false;
             double maxSpeed = 0;
-            using var downloader = new Downloader.DownloadService(downloadOpt);
+            await using var downloader = new Downloader.DownloadService(downloadOpt);
             //downloader.DownloadStarted += (sender, value) =>
             //{
             //    if (progress != null)
@@ -86,7 +86,7 @@ namespace ServiceLib.Common
             //};
             downloader.DownloadProgressChanged += (sender, value) =>
             {
-                TimeSpan ts = (DateTime.Now - totalDatetime);
+                var ts = (DateTime.Now - totalDatetime);
                 if (progress != null && ts.Seconds > totalSecond)
                 {
                     hasValue = true;
@@ -112,7 +112,7 @@ namespace ServiceLib.Common
             //progress.Report("......");
             using var cts = new CancellationTokenSource();
             cts.CancelAfter(timeout * 1000);
-            using var stream = await downloader.DownloadFileTaskAsync(address: url, cts.Token);
+            await using var stream = await downloader.DownloadFileTaskAsync(address: url, cts.Token);
 
             downloadOpt = null;
         }
@@ -145,7 +145,7 @@ namespace ServiceLib.Common
 
             var progressPercentage = 0;
             var hasValue = false;
-            using var downloader = new Downloader.DownloadService(downloadOpt);
+            await using var downloader = new Downloader.DownloadService(downloadOpt);
             downloader.DownloadStarted += (sender, value) =>
             {
                 progress?.Report(0);
diff --git a/v2rayN/ServiceLib/Common/FileManager.cs b/v2rayN/ServiceLib/Common/FileManager.cs
index 4eb97a51..70b09314 100644
--- a/v2rayN/ServiceLib/Common/FileManager.cs
+++ b/v2rayN/ServiceLib/Common/FileManager.cs
@@ -23,7 +23,7 @@ namespace ServiceLib.Common
         {
             try
             {
-                using FileStream fs = File.Create(fileName);
+                using var fs = File.Create(fileName);
                 using GZipStream input = new(new MemoryStream(content), CompressionMode.Decompress, false);
                 input.CopyTo(fs);
             }
@@ -38,8 +38,8 @@ namespace ServiceLib.Common
             try
             {
                 FileInfo fileInfo = new(fileName);
-                using FileStream originalFileStream = fileInfo.OpenRead();
-                using FileStream decompressedFileStream = File.Create(toName != null ? Path.Combine(toPath, toName) : toPath);
+                using var originalFileStream = fileInfo.OpenRead();
+                using var decompressedFileStream = File.Create(toName != null ? Path.Combine(toPath, toName) : toPath);
                 using GZipStream decompressionStream = new(originalFileStream, CompressionMode.Decompress);
                 decompressionStream.CopyTo(decompressedFileStream);
             }
@@ -54,7 +54,7 @@ namespace ServiceLib.Common
             return NonExclusiveReadAllText(path, Encoding.Default);
         }
 
-        public static string NonExclusiveReadAllText(string path, Encoding encoding)
+        private static string NonExclusiveReadAllText(string path, Encoding encoding)
         {
             try
             {
@@ -73,8 +73,8 @@ namespace ServiceLib.Common
         {
             try
             {
-                using ZipArchive archive = ZipFile.OpenRead(fileName);
-                foreach (ZipArchiveEntry entry in archive.Entries)
+                using var archive = ZipFile.OpenRead(fileName);
+                foreach (var entry in archive.Entries)
                 {
                     if (entry.Length == 0)
                     {
@@ -110,7 +110,7 @@ namespace ServiceLib.Common
             }
             try
             {
-                using ZipArchive archive = ZipFile.OpenRead(fileName);
+                using var archive = ZipFile.OpenRead(fileName);
                 return archive.Entries.Select(entry => entry.FullName).ToList();
             }
             catch (Exception ex)
@@ -149,13 +149,13 @@ namespace ServiceLib.Common
                 throw new DirectoryNotFoundException($"Source directory not found: {dir.FullName}");
 
             // Cache directories before we start copying
-            DirectoryInfo[] dirs = dir.GetDirectories();
+            var dirs = dir.GetDirectories();
 
             // Create the destination directory
             Directory.CreateDirectory(destinationDir);
 
             // Get the files in the source directory and copy to the destination directory
-            foreach (FileInfo file in dir.GetFiles())
+            foreach (var file in dir.GetFiles())
             {
                 if (Utils.IsNotEmpty(ignoredName) && file.Name.Contains(ignoredName))
                 {
@@ -165,16 +165,16 @@ namespace ServiceLib.Common
                 {
                     continue;
                 }
-                string targetFilePath = Path.Combine(destinationDir, file.Name);
+                var targetFilePath = Path.Combine(destinationDir, file.Name);
                 file.CopyTo(targetFilePath);
             }
 
             // If recursive and copying subdirectories, recursively call this method
             if (recursive)
             {
-                foreach (DirectoryInfo subDir in dirs)
+                foreach (var subDir in dirs)
                 {
-                    string newDestinationDir = Path.Combine(destinationDir, subDir.Name);
+                    var newDestinationDir = Path.Combine(destinationDir, subDir.Name);
                     CopyDirectory(subDir.FullName, newDestinationDir, true, ignoredName);
                 }
             }
diff --git a/v2rayN/ServiceLib/Common/HttpClientHelper.cs b/v2rayN/ServiceLib/Common/HttpClientHelper.cs
index bd671fee..cabc3f85 100644
--- a/v2rayN/ServiceLib/Common/HttpClientHelper.cs
+++ b/v2rayN/ServiceLib/Common/HttpClientHelper.cs
@@ -27,7 +27,7 @@ namespace ServiceLib.Common
 
             try
             {
-                HttpResponseMessage response = await httpClient.GetAsync(url);
+                var response = await httpClient.GetAsync(url);
                 return await response.Content.ReadAsStringAsync();
             }
             catch
@@ -84,8 +84,8 @@ namespace ServiceLib.Common
             var total = response.Content.Headers.ContentLength ?? -1L;
             var canReportProgress = total != -1 && progress != null;
 
-            using var stream = await response.Content.ReadAsStreamAsync(token);
-            using var file = File.Create(fileName);
+            await using var stream = await response.Content.ReadAsStreamAsync(token);
+            await using var file = File.Create(fileName);
             var totalRead = 0L;
             var buffer = new byte[1024 * 1024];
             var progressPercentage = 0;
@@ -98,7 +98,7 @@ namespace ServiceLib.Common
                 totalRead += read;
 
                 if (read == 0) break;
-                file.Write(buffer, 0, read);
+                await file.WriteAsync(buffer, 0, read, token);
 
                 if (canReportProgress)
                 {
@@ -133,13 +133,13 @@ namespace ServiceLib.Common
             //var total = response.Content.Headers.ContentLength.HasValue ? response.Content.Headers.ContentLength.Value : -1L;
             //var canReportProgress = total != -1 && progress != null;
 
-            using var stream = await response.Content.ReadAsStreamAsync(token);
+            await using var stream = await response.Content.ReadAsStreamAsync(token);
             var totalRead = 0L;
             var buffer = new byte[1024 * 64];
             var isMoreToRead = true;
-            string progressSpeed = string.Empty;
-            DateTime totalDatetime = DateTime.Now;
-            int totalSecond = 0;
+            var progressSpeed = string.Empty;
+            var totalDatetime = DateTime.Now;
+            var totalSecond = 0;
 
             do
             {
@@ -168,7 +168,7 @@ namespace ServiceLib.Common
 
                     totalRead += read;
 
-                    TimeSpan ts = (DateTime.Now - totalDatetime);
+                    var ts = (DateTime.Now - totalDatetime);
                     if (progress != null && ts.Seconds > totalSecond)
                     {
                         totalSecond = ts.Seconds;
diff --git a/v2rayN/ServiceLib/Common/Job.cs b/v2rayN/ServiceLib/Common/Job.cs
index 0cd623fb..4acf7520 100644
--- a/v2rayN/ServiceLib/Common/Job.cs
+++ b/v2rayN/ServiceLib/Common/Job.cs
@@ -8,7 +8,7 @@ namespace ServiceLib.Common
      * http://stackoverflow.com/questions/6266820/working-example-of-createjobobject-setinformationjobobject-pinvoke-in-net
      */
 
-    public class Job : IDisposable
+    public sealed class Job : IDisposable
     {
         private IntPtr handle = IntPtr.Zero;
 
@@ -73,7 +73,7 @@ namespace ServiceLib.Common
             GC.SuppressFinalize(this);
         }
 
-        protected virtual void Dispose(bool disposing)
+        private void Dispose(bool disposing)
         {
             if (disposed) return;
             disposed = true;
diff --git a/v2rayN/ServiceLib/Common/JsonUtils.cs b/v2rayN/ServiceLib/Common/JsonUtils.cs
index d7650d2c..40d0cdfc 100644
--- a/v2rayN/ServiceLib/Common/JsonUtils.cs
+++ b/v2rayN/ServiceLib/Common/JsonUtils.cs
@@ -69,7 +69,7 @@ namespace ServiceLib.Common
         /// <returns></returns>
         public static string Serialize(object? obj, bool indented = true)
         {
-            string result = string.Empty;
+            var result = string.Empty;
             try
             {
                 if (obj == null)
@@ -112,7 +112,7 @@ namespace ServiceLib.Common
             }
             try
             {
-                using FileStream file = File.Create(filePath);
+                using var file = File.Create(filePath);
 
                 var options = new JsonSerializerOptions
                 {
diff --git a/v2rayN/ServiceLib/Common/QRCodeHelper.cs b/v2rayN/ServiceLib/Common/QRCodeHelper.cs
index 7e6e0d08..82d6125e 100644
--- a/v2rayN/ServiceLib/Common/QRCodeHelper.cs
+++ b/v2rayN/ServiceLib/Common/QRCodeHelper.cs
@@ -7,7 +7,7 @@ namespace ServiceLib.Common
         public static byte[]? GenQRCode(string? url)
         {
             using QRCodeGenerator qrGenerator = new();
-            using QRCodeData qrCodeData = qrGenerator.CreateQrCode(url ?? string.Empty, QRCodeGenerator.ECCLevel.Q);
+            using var qrCodeData = qrGenerator.CreateQrCode(url ?? string.Empty, QRCodeGenerator.ECCLevel.Q);
             using PngByteQRCode qrCode = new(qrCodeData);
             return qrCode.GetGraphic(20);
         }
diff --git a/v2rayN/ServiceLib/Common/QueryableExtension.cs b/v2rayN/ServiceLib/Common/QueryableExtension.cs
index 76767656..b8e91433 100644
--- a/v2rayN/ServiceLib/Common/QueryableExtension.cs
+++ b/v2rayN/ServiceLib/Common/QueryableExtension.cs
@@ -17,7 +17,7 @@ namespace ServiceLib.Common
 
         private static IOrderedQueryable<T> _OrderBy<T>(IQueryable<T> query, string propertyName, bool isDesc)
         {
-            string methodname = (isDesc) ? "OrderByDescendingInternal" : "OrderByInternal";
+            var methodname = (isDesc) ? "OrderByDescendingInternal" : "OrderByInternal";
 
             var memberProp = typeof(T).GetProperty(propertyName);
 
diff --git a/v2rayN/ServiceLib/Common/SemanticVersion.cs b/v2rayN/ServiceLib/Common/SemanticVersion.cs
index beea6acc..fd236c89 100644
--- a/v2rayN/ServiceLib/Common/SemanticVersion.cs
+++ b/v2rayN/ServiceLib/Common/SemanticVersion.cs
@@ -28,14 +28,14 @@
                 }
                 this.version = version.RemovePrefix('v');
 
-                string[] parts = this.version.Split('.');
+                var parts = this.version.Split('.');
                 if (parts.Length == 2)
                 {
                     this.major = int.Parse(parts[0]);
                     this.minor = int.Parse(parts[1]);
                     this.patch = 0;
                 }
-                else if (parts.Length == 3 || parts.Length == 4)
+                else if (parts.Length is 3 or 4)
                 {
                     this.major = int.Parse(parts[0]);
                     this.minor = int.Parse(parts[1]);
diff --git a/v2rayN/ServiceLib/Common/SqliteHelper.cs b/v2rayN/ServiceLib/Common/SqliteHelper.cs
index 9faa72ba..ca34319e 100644
--- a/v2rayN/ServiceLib/Common/SqliteHelper.cs
+++ b/v2rayN/ServiceLib/Common/SqliteHelper.cs
@@ -11,7 +11,7 @@ namespace ServiceLib.Common
         private SQLiteConnection _db;
         private SQLiteAsyncConnection _dbAsync;
         private static readonly object objLock = new();
-        public readonly string _configDB = "guiNDB.db";
+        private readonly string _configDB = "guiNDB.db";
 
         public SQLiteHelper()
         {
diff --git a/v2rayN/ServiceLib/Common/StringEx.cs b/v2rayN/ServiceLib/Common/StringEx.cs
index eb9bdafe..81965ada 100644
--- a/v2rayN/ServiceLib/Common/StringEx.cs
+++ b/v2rayN/ServiceLib/Common/StringEx.cs
@@ -25,21 +25,14 @@ namespace ServiceLib.Common
             return chars.Contains(s[0]);
         }
 
-        public static bool IsWhiteSpace(this string value)
+        private static bool IsWhiteSpace(this string value)
         {
-            foreach (char c in value)
-            {
-                if (char.IsWhiteSpace(c)) continue;
-
-                return false;
-            }
-            return true;
+            return value.All(char.IsWhiteSpace);
         }
 
         public static IEnumerable<string> NonWhiteSpaceLines(this TextReader reader)
         {
-            string? line;
-            while ((line = reader.ReadLine()) != null)
+            while (reader.ReadLine() is { } line)
             {
                 if (line.IsWhiteSpace()) continue;
                 yield return line;
@@ -53,26 +46,12 @@ namespace ServiceLib.Common
 
         public static string RemovePrefix(this string value, char prefix)
         {
-            if (value.StartsWith(prefix))
-            {
-                return value.Substring(1);
-            }
-            else
-            {
-                return value;
-            }
+            return value.StartsWith(prefix) ? value[1..] : value;
         }
 
         public static string RemovePrefix(this string value, string prefix)
         {
-            if (value.StartsWith(prefix))
-            {
-                return value.Substring(prefix.Length);
-            }
-            else
-            {
-                return value;
-            }
+            return value.StartsWith(prefix) ? value[prefix.Length..] : value;
         }
 
         public static string UpperFirstChar(this string value)
@@ -82,17 +61,12 @@ namespace ServiceLib.Common
                 return string.Empty;
             }
 
-            return char.ToUpper(value[0]) + value.Substring(1);
+            return char.ToUpper(value[0]) + value[1..];
         }
 
         public static string AppendQuotes(this string value)
         {
-            if (string.IsNullOrEmpty(value))
-            {
-                return string.Empty;
-            }
-
-            return $"\"{value}\"";
+            return string.IsNullOrEmpty(value) ? string.Empty : $"\"{value}\"";
         }
     }
 }
\ No newline at end of file
diff --git a/v2rayN/ServiceLib/Common/YamlUtils.cs b/v2rayN/ServiceLib/Common/YamlUtils.cs
index f87fd63c..94d572b5 100644
--- a/v2rayN/ServiceLib/Common/YamlUtils.cs
+++ b/v2rayN/ServiceLib/Common/YamlUtils.cs
@@ -21,7 +21,7 @@ namespace ServiceLib.Common
                 .Build();
             try
             {
-                T obj = deserializer.Deserialize<T>(str);
+                var obj = deserializer.Deserialize<T>(str);
                 return obj;
             }
             catch (Exception ex)
@@ -36,9 +36,9 @@ namespace ServiceLib.Common
         /// </summary>
         /// <param name="obj"></param>
         /// <returns></returns>
-        public static string ToYaml(Object? obj)
+        public static string ToYaml(object? obj)
         {
-            string result = string.Empty;
+            var result = string.Empty;
             if (obj == null)
             {
                 return result;