Nethawk XR700 - extender not showing in network list

Hi

I recently set up this extender on my network; I have 3 security cameras connected to the extender.

I have an XR700 router, the extender appears on the network list as offline, however I can see another unnamed device online, with a very similar MAC address and has the 3 camera IP's connected and, as well as 2 others, which I am assuming is the

Extender Mac       E8:44:89:5A:39:5F no IP addresses

Unnamed device EA:44:89:0A:39:5F - IP Addresses connected

192.168.1.15    ea-44-89-0a-39-5F    Cam1
192.168.1.16    ea-44-89-0a-39-5F     Cam2
192.168.1.17    ea-44-89-0a-39-5F     Cam3
192.168.1.19    ea-44-89-0a-39-5F     Unknown possibly an old connection
192.168.1.31    ea-44-89-0a-39-5F     Unknown possibly an old connection

What could be the reason why the actual extender is not showing online and all connectins are being made to this unnamed device with a similar address.

Also Norton security flagged some messages yesterday that "There is an attacker on the network" with Threat name ARP Spoofing. Could this error message be generated due to multiple IP's connecting via the same MAC address?

Any help is welcomed.