Presented herein are techniques to facilitate secure communications with an Application Function (AF) for a client device that does not support Authentication and Key Management for Applications (AKMA) functionality. In one example, a method includes obtaining, by a user plane function (UPF), a first uplink data packet from a client device, wherein the first uplink data packet is to be communicated to an application; determining, by the UPF based on the first uplink data packet, whether the client device supports AKMA functionality; based on determining that the client device does not support the AKMA functionality, buffering at least the first uplink data packet by the user plane function and determining whether the application supports the AKMA functionality; and based on determining that the application supports the AKMA functionality, performing AKMA functionality by the UPF for the client device for data communications between the client device and the application.