Recently purchased the TP Link AV600 powerline kit (WPA-4220 Kit) from Amazon. The connection was set up correctly and everything works fine along with the Wifi. 

Although at occassions (this has happened twice this week), the wifi disconnects from all devices. It is still showing up on the wifi search but when i try and connect it asks for the password again. When i put in the password it says "Invalid password". It keeps on doing this until i switch off the plug and switch it on again.  After switching on the plug everything is fine.

The Adapter has two parts in the kit; the main powerline adapter is connected via ethernet cable to the router and plugged to the main supply right next to the router downstairs. The wifi adapter is connected upstairs (one floor up), in the room. Wifi signals are perfect, just the issue mentioned above which keeps on coming on weekly basis is abit annoying.