A master controller (104, 304) comprising: a processing resource; and a memory resource storing machine-readable instructions to cause the processing resource to: create a plurality of groups of access points, APs (108, 208), connected to a plurality of local controllers, wherein the groups are created such that each group comprises APs (108, 208) on the same AP channel or the same subgroup of AP channels; move a first subset of the plurality of APs (108, 208) which is connected to a first local controller of the plurality of local controllers to at least one other local controller of the plurality of local controllers; upgrade the first local controller; move APs (108, 208) associated with a group among the plurality of groups of APs (108, 208) to the upgraded first local controller; upgrade the APs (108, 208) associated with the group of the first local controller; move a second subset of the plurality of APs (108, 208) which is connected to a second local controller of the plurality of local controllers to at least one other local controller of the plurality of local controllers; upgrade the second local controller; move APs (108, 208) associated with a second group among the plurality of groups of APs (108, 208) to the second local controller; and upgrade the plurality of APs (108, 208) of the second group. a processing resource; and a memory resource storing machine-readable instructions to cause the processing resource to: create a plurality of groups of access points, APs (108, 208), connected to a plurality of local controllers, wherein the groups are created such that each group comprises APs (108, 208) on the same AP channel or the same subgroup of AP channels; move a first subset of the plurality of APs (108, 208) which is connected to a first local controller of the plurality of local controllers to at least one other local controller of the plurality of local controllers; upgrade the first local controller; move APs (108, 208) associated with a group among the plurality of groups of APs (108, 208) to the upgraded first local controller; upgrade the APs (108, 208) associated with the group of the first local controller; move a second subset of the plurality of APs (108, 208) which is connected to a second local controller of the plurality of local controllers to at least one other local controller of the plurality of local controllers; upgrade the second local controller; move APs (108, 208) associated with a second group among the plurality of groups of APs (108, 208) to the second local controller; and upgrade the plurality of APs (108, 208) of the second group. create a plurality of groups of access points, APs (108, 208), connected to a plurality of local controllers, wherein the groups are created such that each group comprises APs (108, 208) on the same AP channel or the same subgroup of AP channels; move a first subset of the plurality of APs (108, 208) which is connected to a first local controller of the plurality of local controllers to at least one other local controller of the plurality of local controllers; upgrade the first local controller; move APs (108, 208) associated with a group among the plurality of groups of APs (108, 208) to the upgraded first local controller; upgrade the APs (108, 208) associated with the group of the first local controller; move a second subset of the plurality of APs (108, 208) which is connected to a second local controller of the plurality of local controllers to at least one other local controller of the plurality of local controllers; upgrade the second local controller; move APs (108, 208) associated with a second group among the plurality of groups of APs (108, 208) to the second local controller; and upgrade the plurality of APs (108, 208) of the second group.