FYI that I do not work for NOW, I am simply a NOW customer trying to help I am a Community Contributor This means that I know a lot about the service and like you I am still a customer. For any account issues you’ll need to contact staff via customer support.
As other have mentioned, enabling 'DoH' (DNS over HTTPS) clears the problem for browsers.
For other devices I had to be more creative, as the provided router doesn't give the option to change the DNS given out.
If you can't manually alter the DNS of your devices to something more reliable (such as 126.96.36.199 & 188.8.131.52 or 184.108.40.206) then you can turn of the DHCP service on your NowTV router and use another server/old router to serve up IP addresses with the NowTV router as the gateway/default route and a different DNS... not for the faint of heart though!