A method performed in a user equipment, UE, (1) and a gateway (2) for data communication in a 3GPP network via an access point name, APN, capable of providing support for packet data network, PDN, connectivity using a first internet protocol version and PDN connectivity using a second internet protocol version. The method comprises the steps of the UE requesting (S1) dual stack PDN connectivity from a gateway (2) and receiving (S2) a single IP address on either the first or the second internet protocol version from the gateway (2) and further receiving (S3) from the gateway (2) a cause code indicating that only the assigned PDN and internet protocol version is allowed.