On Cisco wifi, we started seeing signal fluctuations since 1-2 months. The only change that was done to change windows user preference from 2.4 GHz Radio to 5 GHz radio through a windows group policy change. But this was done in response to the problem reported by certain users.We have lately discovered that some of the neighboring APs opt for same frequency band at 5.0 GHz and also at 2.4 GHz. Reboot of these APs have not helped to choose different frequency band by these APs.Channel assignment is set to be auto and we cannot change it to static though we are aware of definitive AP positions at all floors in campus. The reason being that the controller serves APAC and we do not know the definite / relative positions of different APs.The wireless survey conducted before (when there was no complaint on wifi) did show presence of co-channel interferences in certain areas, but SNR was seen to be very good in all areas of all the floors. For skype, we have call drop or call noisy complain from users across the three floors irrespective of if they are connected to wifi or LAN. We are using Cisco WLC 5520 controller. Regards,Vikash SoroutHand-phone : +91-9013866229Email: vikash_sorout@yahoo.com