Are you sure you need the Ethernet extension cable instead of an Ethernet cable?
They are different with different ends.
The extension cable will connect to itself since the ends are opposite.
An Ethernet cable has the same ends to connect two devices together.
Edited by Wayne P. (10/19/16 09:38 PM)
Humminbird Helix 12 SI, 1198c SI, 1198c SI, ONIX 10 SI NT, 360, RC-1