Download the Fing app to (preferably) an Android phone or tablet, and it will give you chapter and verse on every device connected to your hub, whether WiFi or wired.
It does work on iThingys, but not as well, as Apple demand a certain level of crippling, so you have to work a bit harder to identify devices on this version.
Firstly i am assuming you have the NowTV Hub Router ?
If so, there is another method to check what devices are connected to the Hub Router over both WiFi and Ethernet at any particular given time.
What you need to do is go to My Account whilst logged in on here, then select Technical Checks, then let the system carry out an online health check (may take up to 5 minutes).
Then click the green down arrow below "Broadband & Phone every thing looks good", then click the green button saying "Find Out More".
You should then see a summary screen page with the measured incoming internet speed at the Hub Router, where towards the bottom of the screen there will be a list of devices that is connected to the NowTV Hub Router at the time of the test.