TP-Link AV500 Powerline ac Wi-Fi Kit

[simonpreston]

In that case there is an issue somewhere in your wiring mate. Perhaps get an electrician in to test continuity or find out if something else is wired incorrectly

In 4 completely different houses?

[3dcandy]

Perhaps you have taken something with you to all the houses.... could be something as simple as an extension lead/lamp/piece of equipment
Believe me I've seen enough houses that have stupid things like no earths connected correctly or even in one house ALL the ring main sockets upstairs wired back to front (ie. live and neutral swapped) but because they all were wrong it worked (to clarify the wires were the wrong colours but because they were all the wrong colours it worked as live to live and neutral to neutral)