The network administrator should enable WPA2 on the router to secure the wireless network. WPA2 (Wi-Fi Protected Access 2) is currently one of the most secure encryption methods for wireless networks, providing strong security measures to prevent unauthorized access. WEP is an older encryption standard that is much less secure than WPA2, while disabling SSID broadcasting and changing the default channel can improve security, they are supplementary measures and do not encrypt the data transmitted over the network.