Network Stability Problem

HI everyone!
I m working on zigbee formerly series 2 modules using znet2.5 firmware. The zigbee network is showing much unstability as often it gives different results for atnd command run back to back. Also when i use range test in XCTU software it suddenly start giving timeouts (after giving some successful data transfer initially) which quite disappointed me.
last but not the least is the range problem that according to datasheet its urban range is 30m but it is not giving me more than 5m. I will also be interested in finding that what are the factors and parameters which can affect the range and data transfer authenticity of module?
your precious replies awaited kindly update me as m really stuck in this situation!!

Thanks and regards

Hi Amir,

What firmware version is running on the modules (ATVR)? What antenna type are they (wire, chip, SMA, U.fl)? Are you sending unicast transmissions or broadcast transmissions (DH and DL commands)?

Message was edited by: damons

hi Damons:
sorry for late reply. I am using Znet2.5 Coordinator API ver. 1147 on cordiantor and Znet2.5 Router/End Device AT ver 1247 on my router. I am using external antenna on my cordinator and chip, whip and u.fl antenna (am using three routers currently) on routers. Mostly i m sending unicast transmission as the network gets very slow in broadcast.
Moreover, i want to know that is firmware or its version affects the network stability or transmission??
awaiting you cooperation

Thanks and regards,

Amir Ahmed