Problem connecting TC40 Aruba network

Hello I have an issue connecting a TC40 to Aruba WLAN. The problema is as follow. The TC70 connects to 80Mhz if we desactivate ths freuqency on the Wireless Controller this TC70 never connects again in 40 MHZ until we resart the Controller or the AP,

Is there a way to fix this problema without resenting the AP or WLC?

Can I forcé the TC70 to connect only in 40MHZ?

Thanks in advance for your help