Powerline wifi range extender - wifi devices frequently lose connection

Hi there, 

I have a poweline 500 system distributing wired ethernet around the house and it works great. 

However, the wifi component of the XWN5001 is a big problem. When in use, devices connected to it frequently lose internet connection, although remain connected to the wifi. This plays havoc with smarthome devices in the area which go unresponive and lose their config. 

I want to extend the range of my wifi network, but this product does not seem to be a stable solution. Can anyone comment on a robust way to do it? Should this product be more reliable? Or is a dedicated WiFi range extender a better option? 

Thanks.