1, you can check to see if there is no charging head and data cable problems; It is also possible that the phone does not recognize the fast charge function of the charger;
2, first use the battery of the phone until the automatic shutdown, and then plug in the original charger to charge, do not turn on and keep the shutdown charging, until the breathing light turns green 100% power and then turn on. Slow charging no fast charging may be that your phone is charging by usb charging, the above method can be switched to AC charging (that is, fast charging);
3, enter the phone's [Settings] - [About the phone] - [MIUI version], and then click 5 times in a row, you can open the [developer options], close the USB debugging, revoke all USB debugging authorization, and then return to the status information in the setting to see whether it is in AC power charging;
4, if you still can't use fast charge, you can only get the phone to the after-sales point for maintenance.
Of course, the wifi module and the charging module are two parts, the wifi module does not affect the charging, as well as the fast charging of the mobile phone.