Had powerline adapters running through the house for years now and in the last few days nearly all have stopped. any that i plug into one half of the house work fine, but the others dont. 

I don't think there is anything wrong with the units, I just need to find what/where the problem is and how to fix it. Anyone had experience of this? or can help with where to start looking? I guess its going to be in the electrical sstem of the house somewhere? 

I'm running the AV600 adapters (TL-PA4010P KIT)

the top ights are on, the bottom lights are on but the middle one the Powerline LED is off.