Yes the admin port can be used during normal operation. However, the admin port cannot be used for AP to controller communication or to provide services to wireless clients. The admin port should never be used to authenticate users against NAC or a radius server and should never have an IP address assigned that is in the same subnet as you authentication servers even if the port is powered down. The admin port should only be used as an out-of-band management port for GUI access only. It should have no connectivity to the access points or the production data network.