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:
Connect your Hub Two to your laptop or computer using an Ethernet cable.
Open your web browser and enter "192.168.0.1” in the address bar.
SelectMaintenanceand enter “admin” and “nowtv” as the username and password.
SelectWirelessand then2.4 GHz Wireless Settings.
Scroll down to “Wireless Access Point” and uncheckSynchronise 2.4GHz and 5GHz Settings.
In the ‘Name (SSID)’ box, Change the network name to distinguish it from the current network (e.g. add “_2.4G” to the current name). SelectApply.
Check the network name has been updated, and then select5GHz Wireless Settings.
To be able to see easily which network is which on your devices, change the ‘Name (SSID)’ here too (e.g. add “_5G” to the current name). SelectApply.
That’s it. SelectLogoutat the top of the screen to exit.
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.