A method of operation of a cellular communications system is disclosed. The method comprises: at a MME: receiving an attach request from a UE; sending a location update request to a HSS; receiving a location update acknowledgement; sending, to a DNS, a DNS query request comprising an APN FQDN; receiving a DNS query response comprising information that indicates candidate PGWs that satisfy the DNS query request and at least two PGWs belonging to a same PGW set; selecting the first PGW; sending, to a SGW, a first create session request that comprises information that indicates the first PGW; receiving a first create session response; sending an attach accept to the UE; and at the SGW: receiving the first create session request from the MME; forwarding the first create session request to the first PGW; receiving the first create session response; and forwarding the first create session response to the MME.