Losing ability to charge wirelessly

My phone randomly refuses to charge wirelessly on any charger but the OEM Nexus charger. Even that takes a bit of finagling. I thought it was the other chargers. Bought a Choetech and it worked for about a month, then started having issues. Would disconnect after anything from a few seconds to a few hours. Thought it was the charger so I bought a Samsung charger. Same thing. Worked great for a while and then the same issues started. Friend's phone (Samsung 7) and wife's phone (Nexus 5) work fine on both chargers. Anyone have any idea why this would start happening?