A couple of people have mentioned this recently.
Here's one example thread below.
My Roku Stick Plus is still running fine with the NOW App using NOW Broadband.
Would be interested if the people affected are using the same ISP / Router to eliminate that out of the equation.
Thanks for getting back.
It looks there is a general problem looking at those other threads.
In the end I have removed and reinstalled the app and it works.
The installation took much longer than usual so I wonder what it's doing.