diff --git a/mobile/lib/screens/login_screen.dart b/mobile/lib/screens/login_screen.dart
index 2618147..66301dc 100644
--- a/mobile/lib/screens/login_screen.dart
+++ b/mobile/lib/screens/login_screen.dart
@@ -1,6 +1,8 @@
+import 'package:dio/dio.dart';
 import 'package:flutter/material.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 
+import '../config.dart';
 import '../services/auth_api.dart';
 import '../services/call_service.dart';
 import '../services/im_service.dart';
@@ -92,14 +94,52 @@ class _LoginScreenState extends State<LoginScreen> {
         MaterialPageRoute(builder: (_) => const HomeScreen()),
       );
     } on AuthException catch (e) {
-      setState(() => _error = e.message);
+      await _fail(e.message);
     } catch (_) {
-      setState(() => _error = '登录出错了，请稍后再试');
+      await _fail('登录出错了，请稍后再试');
     } finally {
       if (mounted) setState(() => _logging = false);
     }
   }
 
+  /// 登录失败：在提示下方附上服务器自检结果，方便远程定位是哪一段不通
+  Future<void> _fail(String msg) async {
+    final parts = [msg];
+    try {
+      parts.add(await _diagnoseServer());
+    } catch (_) {
+      // 自检本身失败不影响原提示
+    }
+    final sdkErr = IMService.instance.lastConnectError;
+    if (sdkErr != null && sdkErr.isNotEmpty) parts.add('消息组件报告：$sdkErr');
+    if (mounted) setState(() => _error = parts.join('\n'));
+  }
+
+  /// 逐个探测三个服务端口：能拿到任何 HTTP 响应就算通
+  Future<String> _diagnoseServer() async {
+    final dio = Dio(BaseOptions(
+      connectTimeout: const Duration(seconds: 5),
+      receiveTimeout: const Duration(seconds: 5),
+    ));
+    Future<String> probe(String label, String url) async {
+      try {
+        await dio.get(url);
+        return '$label通';
+      } on DioException catch (e) {
+        return e.response != null ? '$label通' : '$label不通';
+      } catch (_) {
+        return '$label不通';
+      }
+    }
+
+    final results = await Future.wait([
+      probe('账号服务', '$authApiBase/api/health'),
+      probe('消息接口', '$apiAddr/'),
+      probe('消息长连接', 'http://$serverHost:$wsPort/'),
+    ]);
+    return '自检：${results.join('，')}';
+  }
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(
diff --git a/mobile/lib/services/im_service.dart b/mobile/lib/services/im_service.dart
index 2bd398d..404ec60 100644
--- a/mobile/lib/services/im_service.dart
+++ b/mobile/lib/services/im_service.dart
@@ -36,6 +36,9 @@ class IMService extends ChangeNotifier {
   /// 与服务器的连接状态（断网横幅用）
   ConnectStatus connectStatus = ConnectStatus.idle;
 
+  /// 最近一次连接失败的原始错误（诊断展示用）
+  String? lastConnectError;
+
   /// 是否已登录
   bool loggedIn = false;
 
@@ -108,12 +111,14 @@ class IMService extends ChangeNotifier {
           connectStatus = ConnectStatus.connecting;
           notifyListeners();
         },
-        onConnectSuccess: () {
-          connectStatus = ConnectStatus.success;
-          notifyListeners();
-        },
         onConnectFailed: (code, error) {
           connectStatus = ConnectStatus.failed;
+          lastConnectError = '$code $error';
+          notifyListeners();
+        },
+        onConnectSuccess: () {
+          connectStatus = ConnectStatus.success;
+          lastConnectError = null;
           notifyListeners();
         },
         onKickedOffline: _forceLogout,
@@ -191,6 +196,10 @@ class IMService extends ChangeNotifier {
   /// 登录（init 之后调用）。userID/token 来自公司账号登录接口。
   Future<void> login({required String userID, required String token}) async {
     await init();
+    if (!sdkReady) {
+      // initSDK 返回 false：SDK 没初始化成功，直接登录会无限等待
+      throw StateError('消息组件初始化失败');
+    }
     final user = await OpenIM.iMManager.login(
       userID: userID,
       token: token,
diff --git a/mobile/pubspec.yaml b/mobile/pubspec.yaml
index fc48522..517aab5 100644
--- a/mobile/pubspec.yaml
+++ b/mobile/pubspec.yaml
@@ -1,7 +1,7 @@
 name: changlian
 description: 畅联 —— 公司内部通讯 App（手机端）
 publish_to: "none"
-version: 1.0.1+2
+version: 1.0.2+3
 
 environment:
   sdk: ">=3.6.0 <4.0.0"