After 10.41 upgrade ACS may run and channels and width may be changed
ACS (auto channel select) may run and change channels and channel width from previously configured settings.
BGN radio may now be 40 MHz including all channels rather than 1,6 and 11 only.
AN/AC radios previously set to 20 MHz width many be 40 or 80 after upgrade.
If an AP prior to upgrading to 10.41.01 code had used ACS to select its currently running channel is upgraded to 10.41.01 code after upgrade that AP will run ACS again and potentially change the channel and could also change the channel width previously set to 20 MHz to 40 or even 80 MHz channel widths.
10.41.01.0082 has resolved this issue.
Workaround: If you drop down the channel box and select the same channel as you are currently running, and click save at the bottom of each AP's radio settings the AP will retain its current settings after the upgrade.
The new Auto Channel Selection (ACS) (10.41.xx code)
ACS provides an easy way to optimize channel arrangement based on the current situation in the field. An optimal solution is provided only if ACS is triggered on all APs in a deployment, or all APs placed in a distinct area like a floor. ACS forces the channel width selection of the involved APs to Auto width or 20Mhz. The ACS algorithm selects the optimal channel width for all the selected APs and places each AP on the best channel available in its area. Use the Channel Inspector Report to visualize why the AP was placed on the selected channel. Triggering ACS on a single AP or on a subset of APs can be useful but it is not an optimal solution. The ACS algorithm places the selected APs as best it can considering the channels occupied by other operating APs. ACS relies on the RF channel information observed at the time it is triggered. Once an AP has selected a channel, it remains operating on that channel until you change the channel or trigger ACS again.