Cant get rancher-net to work properly, IPV6 issue?

It seems the rancher-net is not working properly, logs show some errors such as:

INFO: Running /var/lib/cattle/download/iptables/iptables-2-7931ce6fa4d4deb51a429cdea62546151d044b616a3a35a5b4011ac102187cd2/
SIOCSARP: Invalid argument

Looking around, it seems that maybe it’s related with ipv6.
How can i disable ipv6 with rancherOS (installed on HD) ?

Is there anything else I should try ?