Sophos XG 18.04 setting "TCP Appropriate Byte Count " not possible

Hi all,

I would like to set the option "set advanced-firewall tcp-appropriate-byte-count on" but this option is not available in XG 18.04 on my system.

show advanced-firewall show the option as "off" as you can see below, but there is no parameter to enable it anymore?

console> show advanced-firewall
        Strict Policy                           : on
        FtpBounce Prevention                    : control
        Tcp Conn. Establishment Idle Timeout    : 10800
        UDP Timeout                             :
        UDP Timeout Stream                      : 60
        Fragmented Traffic Policy               : allow
        Midstream Connection Pickup             : off
        TCP Seq Checking                        : on
        TCP Window Scaling                      : on
        TCP Appropriate Byte Count              : off
        TCP Selective Acknowledgements          : on
        TCP Forward RTO-Recovery[F-RTO]         : off
        TCP TIMESTAMPS                          : off
        Strict ICMP Tracking                    : off
        ICMP Error Message                      : allow
        IPv6 Unknown Extension Header           : deny

Thanks