Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a relay user equipment (UE) may establish a sidelink unicast link with a remote UE via a sidelink signaling interface. The relay UE may identify configuration information for an adaptation layer of the sidelink signaling interface, the configuration information including at least one of: a remote UE identifier associated with the sidelink unicast link for a relay service, bearer identifier information identifying one or more bearers between the remote UE and a network entity for the relay service, a radio link control (RLC) channel mapping between a bearer identifier and one or more RLC channels, or data routing information associated with the relay service. The relay UE may relay communications between the remote UE and the network entity based at least in part on the configuration information. Numerous other aspects are described.