I suggest if your RSSI is below 500 (just like mine), and even you orient the antenna in different positions and still RSSI is below 500, you can increase it by adding a passive antenna (also known as Stinger) on your motorola canopy subscriber module. This will increase the effective area of your motorola canopy antenna and will capture more power (resulting in an increase of RSSI). You can make your own Stinger too if you want.
Power (RSSI) = Power Density X Effective Area
Low RSSI level affects your antenna's upload and download efficiency. This will also result to high jitter value. High jitter value will cause intermittent connection.