Connection issues solved.
I switched it on and off on both handset & app, unloaded and reloaded the app, removed the blanket from the app & reloaded it, but the issues of no connection persisted.
Then, I had an idea to reset my router just in case it had automatically been upgraded in any way by the ISP. (Pressed the tiny reset button for 30 s).
Gave it a minute then reloaded the CosyNight app and everything was back to normal. All connections working as they should and everything fully functional. Maybe a slight code change had been loaded onto the router which affected the communication between the CosyNight app and router security??
Hope this helps anyone else with similar issues because when it's all working as it should; it really is a great item.