The official development board of stm32 uses PB14 to connect the INT pin of DP83848
Currently, the INT pin of Qiming DP83848 is only pulled up and not connected to PB14.
PB14 is currently connected to USB_HS_DM.
If you want to test plugging and unplugging the network cable, you can only fly the cable yourself. At the same time, USB_HS_DM cannot be used.