Why the hell is my AC1200 Dual Band Wifi Range Extender inconsistent?

I bought a AC1200 Dual Band Wifi Range Extender last week. I installed this wifi extender last week with help from a Netgear rep because the WPS (Wifi Protected Setup wasn't working). The first few days, the signal and connection was fairly reliable. I did countless speed tests to see what my optimal mbps was with an ethernet cable, 2.4GHZ and then 5GHZ network. When I did a speed test check with 5GHZ with the wifi extender, I got nearly the same speed as when I connected my laptop via an ethernet cable. Everything was good! Since those first few days, I've been having a lot of connection issues. I tried so many things and various electrical outlets. The 2.4GHZ and 5GHZ networks are inconsistent as hell and I often either have to reconnect to a network via internet settings or I have to take the wifi extender out of its current electrical outlet and put it in a new one. What is going on?