What is an acceptable RSSI range for sensors?
-30 dBm thru -75 dBm.
If more than -30 dBm, move the Bridge further away from the sensor.
If less than -75dBm, move the Bridge closer to the sensor or analyze the environment to see if there are any RF interfering materials between the Bridge and sensor (thick walls, metal, other systems operating on the same frequency). In the latter case, move the Bridge around/away from these interfering materials but also closer to the sensor.