I have also encountered this malfunction. The reason for the malfunction here is that the backhaul route in the tplink router device is not configured. Need to write the IP address of switch vlan1 in the router。
Thank you very much for your help. I disassembled the test switch and found the M4T28-BR12SH1 component. Looking for new M4T28-BR12SH1 components. I will also update the device status after replacing the new components.