1. Check the configuration and did not find the root cause. Make a local test and find the reason.
Configuration is below:
service-set name KOSEmployees id 0
traffic-profile id 0
security-profile id 0 ///It invokes security profile 0
dhcp trust port
security-profile name Security_Profile id 0
wpa-wpa2 authentication-method psk pass-phrase cipher XXXXX encryption-method tkip
2. After confirmed, customer use TKIP encryption method. This method cannot support 8021.11n. So even cusotmer configuration 802.11n radio type, the maximum speed is 54M. Change the encryption method to CCMP and test it works fine.