Payload loopback functionality is not supported on ATM-over-SHDSL interfaces. [J-series Services Router Basic LAN and WAN Access Configuration Guide]
The J-series Services Router Advanced WAN Access Configuration Guide incorrectly states that you can use the J-Web interface to configure the accounting option for a discard action for IPv6 firewall filters. You can configure the accounting option for a discard action only for IPv4 (not IPv6) firewall filters.