A shared Radio Network Node, RNN, and a method for managing overload in a core network. The shared RNN is configured to serve a wireless device, and the wireless device and the RNN are operating in a wireless communications network connected to the core network. The RNN receives a connection request from the wireless device, wherein the connection request comprises a mapping parameter configured to map to an MME connected to the RNN. Further, the MME is logically partitioned into several MMEs and configured to support multiple MME Codes, MMECs, each of which MMECs is pointing at a sharing operator. The mapping parameter comprises an MMEC configured to map to one MMEC supported by the MME. Further, the RNN rejects or redirects the connection request when the MMEC configured to map to one MMEC supported by the MME is associated with an overload action.