We have found that 1832I series APs of -Z domain is not able to get power level of 17 dBm on UNI-1 channel on code 8.5.x.x or lower.:
But at the latest codes, say 8.10.183.0, AP supports power level upto 17 dbm:
Total Supported Power Levels:7
Allowed total powers(dBm):
17 14 11 8 5 2 1
If you are facing the same issue at 8.5.x.x or lower then it is recommended to gold star version of Cisco, i.e.8.10.183.0
