The customer reports that the serial port on the newly delivered U1930 is printing error messages "lsw flush" and "phy 1 is invalid" all the time, which affects the configuration, as shown in the following figure.
Ask the customer to connect the device to a switch through an Ethernet cable. The alarm information printing stops and the fault is rectified.
According to the messages, the error is related to the LAN switch. The fault is caused by network problems. Ask the customer to check the network. The customer finds that no network cable is connected to the U1930.