A method of operating a first user equipment (UE) in a wireless communication system is disclosed. The method includes performing an access stratum (AS) configuration procedure with a second UE by the first UE, and transmitting a radio resource control (RRC) message to a base station (BS) based on failure of the AS configuration procedure by the first UE. The RRC message includes information about a destination identifier (ID) of a unicast link related to the failure of the AS configuration procedure.