RSSI Threshold allows the AP to kick a wireless client when it goes below the set RSSI (Received Signal Strength Indicator) value. This prevents a common issue wherein a client device is still connected on an AP further away, displaying low signal status, even when the device is closer to another AP.
E.g. RSSI Threshold set to -75 dBm. When the client’s RSSI drops to -76 dBm as it moves further away from the connected AP, the AP will kick the client to allow it to connect to another AP with better signal quality.