NAC manager can support up to 4 NAC gateways per switch for redundancy.
It is a configurable parameter which it allows you to configure up to four redundant NAC Gateways per switch in the Add
or Edit Switches in NAC Appliance Group
In the NAC manager, go to Options->Display->Display Counts
Please notes that the maximum number of NAC gateway is 4
After the change, the number of NAC gateway will be changed based on the NAC gateways you have specified in the Display counts