I 've just sorted this problem .

I've just sorted this problem. This device had been working perfectly on our home wifi connection until 2 days ago so I had no reason to suspect our wifi router. However I thought i'd check and somehow the device's MAC address had 'disappeared' from the MAC address filtering allowed list. How does that happen? Anyway, I reentered the MAC address into the router and it connected straight away. I suspect this might reoccur and I have no idea how it deleted itself from the list, however, at least I know how to rectify it next time.