Network card (DX4020, C900TTL-E, C900V2) will not respond to telnet after executing the ARP command.
Double check the MAC address of the unit. Due to the small size of the type that is used to print the MAC address, sometimes some of the entrys are not exactly as they may appear. The most common misreads are the letter B, which can appear to be an 8, and vice versa. Also sometimes the number 5 in the address can appear to be a 6. Carefully read the MAC address and make the appropriate changes as needed.