Now routers are poor for WiFi. You can mess around with settings until the cows come home but you will have no luck.
The TT hub has antennas that point the WiFi into the property.
The Now Hub looks like a Sky set-top-box and points the WiFi to the ceiling (the PCB is is lying horizontal not vertical)
Invest in a mesh WiFi or switch ISPs (but not to Sky which has the same hardware)
Oh yeah - sky using MER is very non-standard.
If you ever switch again, stay away from Now or Sky if you want WiFi from their routers.
If you do use them, use a Mesh for the WiFi. I use 4 BT Discs.