some solution
upgrade 3.0 works only from 2.9.50
i've tested od rb133 and 500
add chain=forward protocol=tcp tcp-flags=syn connection-limit=100,32 action=drop comment="connection limit" disabled=no
0 name="queue1" target-address=192.168.1.9/32 dst-address=0.0.0.0/0 interface=all queue=default priority=8 limit-at=0/0
max-limit=163840/163840