diff --git a/backend/app/main.py b/backend/app/main.py
index 370d548..db524b0 100644
--- a/backend/app/main.py
+++ b/backend/app/main.py
@@ -112,3 +112,9 @@ def health_check():
         status["db"] = "error"
         status["status"] = "degraded"
     return status
+
+
+@app.get("/api/health")
+def api_health_check():
+    """API 路径下的健康检查（用于前端通过 /api/ 代理访问）"""
+    return health_check()
diff --git a/backend/app/services/check_service.py b/backend/app/services/check_service.py
index a3bcd56..280c57d 100644
--- a/backend/app/services/check_service.py
+++ b/backend/app/services/check_service.py
@@ -103,8 +103,10 @@ class CheckService:
                 "online": online_count,
                 "offline": offline_count,
             }
-        finally:
-            ssh.close()
+        except Exception:
+            # 连接异常时清除缓存，下次自动重连
+            _conn_pool.pop(olt_id, None)
+            raise
 
     def check_single_device(self, device_id: int) -> Dict:
         """通过 SSH 单独查询一台 ONU 设备的当前状态和距离。
@@ -251,8 +253,9 @@ class CheckService:
                 "offline": offline_count,
                 "new_discovered": new_count,
             }
-        finally:
-            ssh.close()
+        except Exception:
+            _conn_pool.pop(olt_id, None)
+            raise
 
     async def scan_olt(self, olt_id: int) -> Dict:
         """仅扫描 OLT，返回发现的设备列表（不写入数据库）"""
@@ -300,8 +303,9 @@ class CheckService:
                 "devices": devices,
                 "duplicates": duplicates,
             }
-        finally:
-            ssh.close()
+        except Exception:
+            _conn_pool.pop(olt_id, None)
+            raise
 
     def _save_duplicate_macs(self, olt_id: int, duplicate_dict: dict):
         for mac, records in duplicate_dict.items():