/ip firewall mangle add action=mark-routing chain=prerouting comment="To AWS" src-address=<Mashine IP> new-routing-mark=aws_route passthrough=no
/ip route add comment="To AWS" distance=5 gateway=<L2TP_AWS_IP> routing-mark=aws_route
Пишу по памяти - синтаксис может быть не верным...