Dual WAN loadbalancing nth method

/ip address
add address=192.168.1.3/24 network=192.168.1.0 broadcast=192.168.1.255 interface=WAN1 comment="" disabled=no
add address=192.168.2.3/24 network=192.168.2.0 broadcast=192.168.2.255 interface=WAN2 comment="" disabled=no
add address=10.10.0.1/24 network=10.10.0.0 broadcast=10.10.0.255 interface=internal comment="" disabled=no

/ip firewall mangle
add chain=prerouting in-interface=internal connection-state=new nth=2,1 action=mark-connection new-connection-mark=conn1 passthrough=yes comment="" disabled=no
add chain=prerouting in-interface=internal connection-mark=conn1 action=mark-routing new-routing-mark=conn1 passthrough=no comment="" disabled=no
add chain=prerouting in-interface=internal connection-state=new nth=1,1 action=mark-connection new-connection-mark=conn2 passthrough=yes comment="" disabled=no
add chain=prerouting in-interface=internal connection-mark=conn2 action=mark-routing new-routing-mark=conn2 passthrough=no comment="" disabled=no


/ip firewall nat
add chain=srcnat connection-mark=conn1 action=masquerade out-interface=WAN1 comment="" disabled=no
add chain=srcnat connection-mark=conn2 action=masquerade out-interface=WAN2 comment="" disabled=no


/ip route
add dst-address=0.0.0.0/0 gateway=192.168.1.1 scope=255 target-scope=10 routing-mark=conn1 comment="" disabled=no
add dst-address=0.0.0.0/0 gateway=192.168.2.1 scope=255 target-scope=10 routing-mark=conn2 comment="" disabled=no