Function description:
1. The Mi Robot Vacuum needs to have certain network speed support to obtain the map. If the network speed is slow, it may not be able to refresh the map.
2. To obtain the map, the robot needs to ensure that the robot is within the scope of wifi. If the machine itself is under the sofa or far away from the router, it may not be able to refresh the map.
3. Some routers and operators do not provide good domain name resolution support for the map server, so the map cannot be refreshed all the time.