Apparatuses, methods, and systems are disclosed for establishing a multi-access data connection. One apparatus includes a processor coupled to a memory storing instructions executable by the processor to cause the apparatus to transmit, over a first access network, a first request to establish a data connection, the first request including a first indication requesting a single-access data connection and a second indication that an upgrade from the single-access data connection to a multi-access data connection is allowed. The instructions are executable by the processor to cause the apparatus to receive a third indication that the single-access data connection is to be upgraded to the multi-access data connection for transporting user-plane traffic over the first access network and a second access network and to establish the multi-access data connection over the first access network and the second access network based on the third indication.