Использую вот такую схему: ECMP и NAT
/ip firewall mangle
add action=mark-connection chain=forward connection-mark=no-mark \
new-connection-mark=con-WAN1 out-interface=ether1-WAN1 passthrough=yes
add action=mark-connection chain=forward connection-mark=no-mark \
new-connection-mark=con-WAN2 out-interface=ether2-WAN2 passthrough=yes
add action=mark-routing chain=prerouting connection-mark=con-WAN1 \
in-interface-list=!lst-WAN new-routing-mark=WAN1 passthrough=yes
add action=mark-routing chain=prerouting connection-mark=con-WAN2 \
in-interface-list=!lst-WAN new-routing-mark=WAN2 passthrough=yes
/ip route
add distance=1 gateway=
1.1.1.1 routing-mark=WAN1
add distance=1 gateway=
2.2.2.1 routing-mark=WAN2
add distance=1 gateway=
1.1.1.1,
1.1.1.1,
2.2.2.1add check-gateway=ping distance=100 gateway=
2.2.2.1add check-gateway=ping distance=100 gateway=
1.1.1.1Официальный