当AWS IoT连接丢失时，可以通过以下代码示例来解决：

1. 使用AWS IoT Device SDK for Python：

import time
from AWSIoTPythonSDK.MQTTLib import AWSIoTMQTTClient

def on_connect(client, userdata, flags, rc):
    if rc == 0:
        print("Connected to AWS IoT")
    else:
        print("Connection to AWS IoT failed")

def on_disconnect(client, userdata, rc):
    print("Disconnected from AWS IoT")
    # 重新连接AWS IoT
    client.connect()

# 初始化AWS IoT MQTT客户端
client = AWSIoTMQTTClient("clientId")
client.on_connect = on_connect
client.on_disconnect = on_disconnect

# 配置AWS IoT端点、证书和密钥
client.configureEndpoint("iot-endpoint", 8883)
client.configureCredentials("rootCA.pem", "privateKey.pem", "cert.pem")

# 连接AWS IoT
client.connect()

# 发布消息
client.publish("topic", "message", 1)

# 循环等待，保持连接
while True:
    time.sleep(1)

2. 使用AWS IoT Device SDK for JavaScript：

const awsIot = require('aws-iot-device-sdk');

// 配置AWS IoT设备
const device = awsIot.device({
  keyPath: 'privateKey.pem',
  certPath: 'cert.pem',
  caPath: 'rootCA.pem',
  clientId: 'clientId',
  host: 'iot-endpoint',
  port: 8883
});

// 连接AWS IoT
device.on('connect', function() {
  console.log('Connected to AWS IoT');
});

// 处理连接丢失事件
device.on('offline', function() {
  console.log('Disconnected from AWS IoT');
  // 重新连接AWS IoT
  device.updateWebSocketCredentials();
  device.subscribe('topic');
});

// 发布消息
device.publish('topic', 'message');

// 循环等待，保持连接
setInterval(function() {
  console.log('Keeping connection alive');
}, 5000);

以上示例代码演示了如何使用AWS IoT Device SDK来处理AWS IoT连接丢失的情况。在连接丢失时，重新连接AWS IoT可以确保设备保持与云端的通信。