Strange item on my network

I'm currently trying to change all the names of items on my home network from the default Unknown-66-32-a4-05-56-c7 types.

I've got all of them bar one at the moment, and I can't work out what it might be.

I have a router downstairs, with a switch plugged into it, cables from that go to an xbox, a youview box, a raspberry-pi, and a pc. Of them, only the raspberry pi has been turned on since i plugged the new router in, so the others should be irrelevant (though the switch is being used).

Another cable from that comes upstairs into my room, where i have another switch, and then a PC, and a linux machine.

So that's a PC, a linux box, and a raspberry-pi, and those i have found the IPs of, and named in the router interface.

But then there is one more, and i don't know what it is.

When I look in the network page in windows, it shows BTHUB5, LEMON, WILL-PC, and then the raspberry-pi media centre options.

It also shows a 4th item, called LINUX-IPCONFIG- which i can't open; it says:

Windows cannot access \LINUX-IPCONFIG- Check the spelling of the name. Otherwise, there might be a problem with your network. To try and identify and resolve network operations, click Diagnose. Error code: 0x80070035 The network path was not found.

clickign diagnose just says that it can't find the "computer", and to make sure it is turned on...

What is this exta item connected to the network? How can i find out what it is, without one by one plugging everything in (which would be a huge pain, as i have cables dangling out of windows to go down to the other floor). Could it be one of the switches?

I also have some VPN software on my computer, could this be causing issues?

(also, is this the correct place for this question?)

Here is the network layout according to the BT Home Hub 5: