FGT 60e + FoprtiAp problem with connecting Mobile devices

Hello every, here is my problem:

I have FGT 60E + FAP21d/FP221. Notebooks successfully coonects to WIFI and can browse internet, but a lot of mobile devices like iphones connects to wifi, but can't reach internet.

At FortiAP log filtered by client i saw this messages:

client-disconnected-by-wtp ============== Action client-disconnected-by-wtp Reason Disassociated because sending STA is leaving (or has left) BSS

I tryed this https://forum.fortinet.com/tm.aspx?m=142151 , but it didn't help.