If you are a mobile phone user, you can't open192.168.31.Please make sure that your mobile phone is connected to the wifi signal of Xiaomi router.
If the Xiaomi router wifi is not connected, it is impossible to open the Xiaomi router background login address using data traffic.
Correct installation method of Xiaomi router
When the Xiaomi router is turned on, connect ADSL Modem (cat) or optical fiber cat with the blue WLAN port of the router with a network cable.
If the broadband access mode is a direct home network cable, then this network cable is directly connected to the blue WLAN port of the router. Connect any other network card interface of Xiaomi router to the computer through the network cable.