From my limited knowledge, your hub router should have two different IP Addresses, where the LAN (Local Area Network) IP address that is used on your internal network on your nowtv hub router is fixed with a default of 192.168.0.1 to access the settings on your router etc.
Where i believe that NowTV use a dynamic IP address when over WAN (Wide Area Network) that they use to connect to the the internet for their customers.
Like i said i have limited knowledge when it comes to networking etc, where hopefully somebody on here who is more knowledgeable will offer you some further assistance.
I am guessing if you internet is running slow that you have tried pressing the reset button at the rear of the nowtv hub router ?
When you go to My Account > Check Service Status on here what does it say about your internet download speeds and wifi signal etc.
There is also a broadband helpline number if you go to My Account > My Package (under moving home).