When using the 5 GHz band on an access point, the channel the access point is broadcasting on is subject to change. For example, if your access points 5 GHz radio is operating on a DFS channel and the radio detects a signal from a radar, it is forced to move to another channel. A radar may be detected from equipment used in such places like an airport, weather station or military base.
If a radar is detected your access point will immediately stop using its current channel, force it to look for another unoccupied channel and then move once it finds an unoccupied channel. This causes any wireless clients connected to the 5 GHz radio to lose their connection to the access point.
802.11h allows wireless clients to move to the new channel used by the access point by notifying the wireless clients about the change of channel. This minimizes data loss when the 5 GHz radio moves to the new channel.
To configure 802.11h navigate to Management > Advanced > Wireless Settings > 5 GHz.
It is disabled by default, and only configurable on the 5 GHz radio.
Only wireless clients that support 802.11h can take advantage of this feature. Any wireless clients that do not support 802.11h will not remain connected to the access point on the new channel, and will lose their connection.
They are required to re-connect to the access point when it moves to a new channel.