It is suggested to eliminate the problem from the following simple points.
1. First make sure that the charger, data cable and mobile phone you use all support 9V2A fast charge.
2. When the charging display is slow charging, how much power is the phone? If the phone power itself is relatively high, it is generally not into the fast charge mode, such as Apple's PD fast charge, when the phone power is as high as 80%, that is, exit the fast charge and enter the Apple 5V charge.
3. Check whether there is debris in the phone interface and data cable connector, and it can be properly cleaned up.
4. Change a data line to observe the test.