Accessing DHCP client list (I think that's what it's called)
 

192.168.0.1 is apparantly my router as this is what I type in to access the settings.
192.168.0.2 is my PC
192.168.0.3 is my tablet
192.168.0.5 is my PS3

These are the only devices that I connect to the internet and I am the only one in the house who uses it so the fact that I don't know what uses 192.168.0.4 is a cause for some concern. Anyone know how I can find out? I looked through all of my Superhubs router settings but it only shows devices that are currently connected. I've tried googling but it only shows how to do it on other routers.

Re: Accessing DHCP client list (I think that's what it's called)
 

It's not necessarily a cause for concern, but you can try to determine it from your PC without looking at the DHCP reserve list.

Open the command prompt and ping the address:

ping 192.168.0.4

Next, check your arp cache to see if there's an entry.

arp -a

If it's in the list, it'll give you the MAC address, which you can then look up. If it's not and the ping didn't respond, then it's probably no longer on your network.

Re: Accessing DHCP client list (I think that's what it's called)
 

I wouldn't worry about it - I've just logged on to our SH2AC, went into Advanced Settings, DHCP Reservation, and it shows this -

iPad 192.168.0.14
Olivers-iPad 192.168.0.22
Tivo 192.168.0.15
HughNewPC 192.168.0.7
android 192.168.0.11
Apple-TV 192.168.0.8

Re: Accessing DHCP client list (I think that's what it's called)
 

are you sure you haven't been using the wifi on a mobile phone or maybe you have got a wireless printer or something? The device doesn't have to be using the internet, it just needs to be connected to your network/the shub. A TV could also do it (wireless), blu ray player or Sky box.

Re: Accessing DHCP client list (I think that's what it's called)
 

The fact that 192.168.0.4 is not in the list means nothing uses 192.168.0.4.

[Edit]

What Hugh said.