Unknown Netgear IP address on network (CG3000V2)

First - and let me make it clear, this is just my opinion, there is no reason to conceal the MAC addresses, all it does is make assisting you more challenging. The MAC addresses of your devices are "invisible" outside of your network, or the network to which the device is connected - in most cases, concealing it provides no additional security, and whilst you've probably been told it is unique to your device, that is not entirely true (I have seen Ethernet cards with the same MAC address), and it is also possible (and in fact a trivial task) to "spoof" MAC addresses because the standards do allow for what is termed a "locally administered address". Second - you seem to be suggesting that some part of the ip address indicates a Netgear device - this is incorrect - the IP address is what's called a logical address, the 192.168.0.x network is probably the most commonly used private network range. The first six characters of the MAC address form what is known as the OUI (Organisationally Unique Identifier) and they can be used to get an idea of who manufactured the device, but this should not be considered as definitive - in addition to the ease with which the MAC can be changed, you will find consumer grade products from many manufacturers showing OUIs from apparently unrelated companies - as an example, my Netgear printservers show up as "SERCOMM", and the HP Pavilion laptop I am using is "UNIVERSAL GLOBAL SCIENTIFIC", my daughter's Dell shows up as "Intel" (it does have an Intel wireless card), and I'm also seeing on my network a "Quanta computer", and two "Liteon Technology" which are all Dell laptops (I recognize the NetBEUI names)