In a wireless network, a user equipment (UE) may support reflective quality of service (QoS), where QoS applied to uplink packets is implicitly derived from downlink packets. For example, when the UE receives a downlink packet that includes a reflective QoS (RQoS) indicator and a QoS flow identifier (QFI), the UE may apply the same QoS associated with the downlink packet to an uplink packet with one or more attributes that match the downlink packet. However, for a received downlink encapsulating security payload (ESP) packet that includes an RQoS indicator and a QFI, a modem cannot determine an uplink security parameters index (SPI) and downlink SPI pairing needed to enable RQoS because the uplink/downlink SPI pairing is known only by the upper layer. Accordingly, some aspects described herein enable the modem to learn uplink/downlink SPI pairings for ESP packets and thereby enable RQoS for ESP packets.