The network diagram is as follows:
At a site, iPad and iPhone devices can access the Wi-Fi network normally through the 5 GHz radio of Huawei APs. However, the built-in mail client of the iOS fails the authentication when attempting to access the exchange or hotmail server. As a result, the iOS devices cannot receive and send emails. The fault does not occur when the iPad and iPhone devices access the Wi-Fi network through the 2.4 GHz radio.
Involved Products and Versions:
Huawei dual-band APs of V200R002C00SPC800 and earlier versions, such as AP6010DN-AGN