I'm faicing a problem with my TP-Link AV1000 Powerline adapters, which I use for an IP camera. They were functioning perfectly for half a year, but suddenly, they no longer establish a connection when positioned at the camera's location. Yet, they operate without issue when plugged in next to each other. I have tested all four units one by one, which rules out any individual device breakdown. Additionally, I've made no adjustments to the electrical wiring or the configuration.

Could you provide any clarity into what might be causing this issue?