优化

.vs/Ntpsync/v17/DocumentLayout.backup.json

@@ -68,7 +68,7 @@
               "RelativeDocumentMoniker": "Form1.cs",
               "ToolTip": "D:\\File\\Library\\Tools\\Ntpsync\\Form1.cs",
               "RelativeToolTip": "Form1.cs",
-              "ViewState": "AgIAAIUAAAAAAAAAAAAIwI8AAAAAAAAAAAAAAA==",
+              "ViewState": "AgIAAIUAAAAAAAAAAAAIwI0AAAARAAAAAAAAAA==",
               "Icon": "ae27a6b0-e345-4288-96df-5eaf394ee369.000738|",
               "WhenOpened": "2025-06-27T12:15:25.553Z",
               "EditorCaption": ""

.vs/Ntpsync/v17/DocumentLayout.json

@@ -68,7 +68,7 @@
               "RelativeDocumentMoniker": "Form1.cs",
               "ToolTip": "D:\\File\\Library\\Tools\\Ntpsync\\Form1.cs",
               "RelativeToolTip": "Form1.cs",
-              "ViewState": "AgIAAIUAAAAAAAAAAAAIwI8AAAAAAAAAAAAAAA==",
+              "ViewState": "AgIAAIUAAAAAAAAAAAAIwI0AAAARAAAAAAAAAA==",
               "Icon": "ae27a6b0-e345-4288-96df-5eaf394ee369.000738|",
               "WhenOpened": "2025-06-27T12:15:25.553Z",
               "EditorCaption": ""

Form1.cs

@@ -135,15 +135,23 @@ namespace Ntpsync
                 byte[] ntpData = new byte[48];
                 ntpData[0] = 0x1B; // LI = 0 (no warning), VN = 3, Mode = 3 (Client)
 
+                // 解析 IPv4 地址
+                var ipList = await Task.Run(() => Dns.GetHostAddresses(host));
+                var ipv4   = ipList.FirstOrDefault(ip => ip.AddressFamily == AddressFamily.InterNetwork);
+                if (ipv4 == null)
+                {
+                    return (DateTime.Now, false, $"{host} 无可用 IPv4 地址");
+                }
+
+                IPEndPoint endPoint = new IPEndPoint(ipv4, 123);
+
                 using (var udp = new UdpClient(AddressFamily.InterNetwork))
                 {
                     udp.Client.ReceiveTimeout = 3000; // 3 秒超时
                     udp.Client.SendTimeout    = 3000;
 
-                    udp.Connect(host, 123);
-
-                    // 发送请求
-                    await udp.SendAsync(ntpData, ntpData.Length);
+                    // 发送请求到指定 IPv4 端点
+                    await udp.SendAsync(ntpData, ntpData.Length, endPoint);
 
                     // 接收响应（带超时或取消）
                     var receiveTask = udp.ReceiveAsync();
@@ -161,6 +169,7 @@ namespace Ntpsync
                         return (DateTime.Now, false, $"从 {host} 获取时间失败: 超时");
                     }
 
+                    // Anycast 场景下可能由不同 IP 返回，只要端口正确即可接受
                     ntpData = receiveTask.Result.Buffer;
                 }