Not able to access the DX4020, C900V2 or the C900TTL-E module through telnet after doing the ARP command.
The mac address on the supplied label is written in a very small point font. Because of this, sometimes some of the numbers do not appear correctly because of the size. B's can look like eights, eights can look like B's, fives can look like sixes, etc.
Check the mac address very carefully to make sure that the proper characters are being entered into the ARP -S command. The MAC address is easy to locate, it will be in the format of 00-20-4A-XX-XX-XX. The mac address on our equipment will always begin with 00-20-4A. You will never find the letter o in the MAC, the numbers are hex numbers and will always range from 0 to 9, and A through F.