Apparatuses, methods, and systems are disclosed for measuring access network performance (“ANP”) parameters for a multi-access data connection. One apparatus includes a processor, a first transceiver and a second transceiver that communicate with a mobile communication network via a first access network and a second access network, respectively. The processor establishes a multi-access data connection with the mobile communication network over the first access network and the second access network and receives measurement assistance information. The processor measures at least one ANP parameter using the measurement assistance information and applies a traffic steering rule to uplink data traffic, the traffic steering rule indicating to which of the first and second access networks the uplink data traffic is to be routed based on the measured at least one ANP parameter.