无线网络漫游问题

场景：一个办公室里面装了两个AP，型号：一个5320，一个4320。两个AP的信道已经做过优化。

问题：现在5320AP连接的终端数有30个，4320连接的终端数只有5个。

做了终端与AP的距离测试，即使终端与4320距离更近，但终端还是会连接到5320.

下面是测试终端的部份连接日志：

Session for a MAC authentication user was terminated.Reason:Received client offline message with reason code=3121 

Client 30b4-XXXX-4d69 went offline from BSS 1cab-XXXX-1bb0 with SSID XXXX on AP 1cab-XXXX-1ba0 Radio ID 2. State changed to Unauth. Reason:AP triggered (kick station by fast keep alive). 

Session for a MAC authentication user was terminated.Reason:Received client offline message with reason code=1040.

 Session for a MAC authentication user was terminated.Reason:Received client offline message with reason code=1040. 

 Client 30b4-XXXX-4d69 went offline from BSS 1cab-XXXX-1bb0 with SSID XXXX on AP 1cab-XXXX-1ba0 Radio ID 2. State changed to Unauth. Reason: Successfully roamed to another BSS. 

 STAMGR_MACA_LOGOFF: -Username=XXXX-UserMAC=XXXX-BSSID=882a-XXXX-0690-SSID=XXXX-APName=882a-XXXX-0680-RadioID=2-VLANID=1908-UsernameFormat=MAC address; Session for a MAC authentication user was terminated.Reason:Received client offline message with reason code=1022

请问会是什么原因？