I used lwip_tcpecho project downloaded from LPCOpen Software for LPC43XX|NXP to test Ethernet driver on LPCXpresso4337 board. When I successfully compiled the project and downloaded it into the LPCXpresso board, I connected the board to PC using RJ45 interface. However when I used 'ethtool' command(in Linux) to test whether Ethernet device has been connected, not any devices have been found(I has successfully seen Ethernet device using other board ). When we use wireshark to detect whether PC has received packets from board, not any packets have been found. On the UART output, I always saw "TP ARP output". Any ideas on how to solve it? What can I do in the next step?