Hi,
in addition to the post, to work properly with load balancing the aps should be near one to other. Also the messages to do the roaming between aps are send using multicast. Then you must enable multicast in the aps vlan in order to work properly with load balancing. Somebody can confirm this?
If you have 802.11x, have you tried to enabled at the Privacy tab in wlan service, Key Management Options, with Oportunistic & Pre-Auth option? I have read that this improve the roaming and reauthentication.
Also you have Fast Transition option (802.11r) that improves de roaming at devices that support the standard.
Otherwise I have had problems with band select with iphone devices... In my lab finally I clear this option and I dont have enabled this option in production. I can see clients that sometimes are in 2,4 and sometimes in 5.
We have testing all this options to improve the performance of the network. All the ideas are welcome.
sorry for my english