I will answer your question "How to find the Tmall Elf device with my mobile phone" first. In fact, it is more accurate to say that the App does not record the public IP of the device, but the Tmall Elf Big Data Center records, and the account bound by Tmall Elf is also operated in the Big Data Center (the operation of binding the account of Tmall Elf by App will be sent to the Big Data Center, and all network applications and all operating apps will be sent to the server by the way). As for the Tmall Elf app, how to find the Tmall Elf device by sending remote operation instructions through the mobile phone 4G? It's actually quite simple. After the mobile phone sends a remote control command to the big data center through a network such as 4G or WiFi, the big data center can send a remote operation command to the Tmall Elf device through the network (provided that the account registered by the mobile phone is bound to the account of the Tmall Elf device).