The last couple of days the remote hasn't been changing channels etc at the point of command and the app has had the same problem. The connection to the internet has been intermittent for the last couple of weeks too. Is there a common fault and solution to sort this out?
The dropping of the Internet connection will be a different issue, and if it is dropping that will explain why you're struggling to use the remote app on your phone/tablet. Try rebooting your broadband router and/or moving the NOW TV box into a better place to improve the connection (away from other electrical items, not tucked under the TV or in an enclosed cabinet, plenty of space around it etc.
If the remote control still doesn't work it may need replacing. You can buy a replacement remote from the Sky Store. The link is here