Ring Doorbell 2nd poor wifi

Since purchasing the Ring video door bell (Gen2) from Ring on 01/11/20, I have noticed that the RSSI is fluctuating between 70 - 71. My router is approximately 3 feet away from the door bell so was expecting a better signal. I have since installed a TP-Link WiFi extender in my study which is closer to the video door bell approximately 2 feet away and only a window as an obstruction, and still the RSSI is showing 70. This is causing a delay to the ring app on my mobile phone when someone rings the bell or in the zone area.