XBEE "XBP9B-DMST-002" Range Issue

can’t get more then 400 meter rabge between “XBP9B-DMST-002” modules with “A09-HASM-7” 2.1 dBi Antenna in two devices. after 400 meters RSSI drop and loss connectivity.

previously, i am using same modules with same configuration that modules are working up to 700 to 800 meters (LOC range) distance.

only difference in these modules are ,
Previously i have bough these modules kits from www.EBAY.com they have provided antennas (no any gain information available) with XBEE modules. ebay did not share the Antenna part number. only moudles part number shared.

(Web Link; http://www.ebay.com/itm/Xbee-PRO-S3B-900HP-RPSMA-Wireless-Kit-250mW-28-miles-/321148558576)

Currently i was bought these modules and antennas from www.digikey.com.
(module PN “XBP9B-DMST-002” and Antenna PN “A09-HASM-7”)

kindly confirm what is the possible reason which is causing reduced the successful communication distance from 800 meters to 400 meters.

Hardware Design Engineer

Could be anything from the Configuration of the radios to the gain of the antennas.

It should be noted that Digi does not have any authorized re sellers that Sell product on Ebay.

any suggested antenna part number for these models by you, with whom we will get successful communication range up to 700 to 800 meters. (currently i have used “A09-HASM-7” 2.1 dBi Antenna by digi international)

ok, i have got your point about Ebay. i just gave that link as reference because Ebay.com modules work better (up to 800 meter range) then those modules bought from digikey.com (up to 400 meter range) as previously mentioned.

Have you tried adjusting any of the radios settings from their default state?

Have you configure them for Point to point communicators and adjusted the channel mask to use different frequencies other than the first 20?