A wireless communication network serves a User Equipment (UE) based on a Data Network Name (DNN). An Access and Mobility Management Function (AMF) receives initial signaling for the UE and selects a current Session Management Function (SMF) to serve the UE for the DNN responsive to the initial signaling. The current SMF serves the UE for the DNN. The AMF detects when the UE enters a geographic area while using the DNN. The current SMF transfers a wireless reattach instruction for the DNN to the UE responsive to the detection of the UE entering the geographic area while using the DNN. The AMF receives new signaling for the UE responsive to the wireless reattach instruction and selects a new SMF to serve the UE for the DNN responsive to the new signaling. The new SMF serves the UE for the DNN.