Methods of operating a DU node of a radio access network are disclosed. The DU node is coupled to a CU node over an F1 interface, and the DU node performs a setup procedure with the CU node over the F1 interface for an RRC connection with respect to a wireless device UE. A setup request message is transmitted to the CU node, wherein the setup request message includes an indication of a latest RRC version supported by the DU node. A setup response message is received from the CU node, wherein this message includes an indication of an RRC version supported by the CU node and by the UE. An RRC connection is established with the UE using the RRC version indicated in the setup response message. Related methods of operating a CU node are also discussed.