Bit of a long shot, but if it was me i would try a factory reset on the NowTV Hub Router by holding the reset button on the back of your Router for about 15 seconds and at the same time also factory reset your third party wifi booster.
Then i would go into the Hub Router settings and split the 2.4ghz & 5ghz wifi band on your NowTV Router.
Your Hub Two is dual-band (2.4GHz and 5 GHz). Splitting these bands to create 2 different Wi-Fi networks can help to improve the speed to your devices. Here’s how to do it:
Then try re connecting the wifi booster to your Hub Router.
If still no joy then maybe try holding in the WPS button on the front of the Hub Router to search for wifi devices.
Hmm I have just cancelled my Now TV broadband as whom ever you have on your help desks are about as useful as a chocolate teapot.
I asked a simple question for the details to login into your system if my primary router fails and they couldn't. Get some people who know what they are doing...