I answered your WiFi question here:
It’s unlikely the WiFi AP is causing the RSSI fluctuations. Rather, there’s this thing called “multi-path propagation”, which means that radio waves can travel multiple paths from the beacon to your phone, and depending on the path, the RSSI differs.
E.g., the -79 dBm RSSI is from a packet that went straight from the beacon to the phone. And the -90 might be a packet that bounced off the floor before reaching the phone, which means that some radio wave energy was absorbed during the “bounce”, but also the path was longer, so there was more energy lost on the way. Hence much lower RSSI, which leads to the phone “thinking” that the beacon is further away.
This is why you shouldn’t expect very accurate distance estimations from beacons. Focus more on general proximity to the beacon. If you need something more precise, that’s when our Location Beacons & Indoor Location come in. You can read more about “proximity vs location” in our blog post: