Rancher behing proxy cannot deploy workload

Rancher version 2.0.5
I have 2 systems one behind the company proxy, the other no.
The first do not manage to deploy a workload (trying same workload on both environments)
Installation is the same the one without the proxy works, with proxy doesn’t and gives error on network: “Failed create pod sandbox: rpc error: code = Unknown desc = NetworkPlugin cni failed to set up pod “azep-cb76557b6-7lq9t_default” network: open /proc/sys/net/ipv6/conf/eth0/accept_dad: no such file or directory”
Is it something linked to the proxy’
The only other difference is that one env (the working one) has hosts that are KVM VMs the non working has VMware’s hosts.
Getting really mad in understanding why the same thing do not work on the second env.

Operative system is CentOS 7

I have found another difference between the two environments it seems that the one that works has IPV6 enabled while the non working one has it disabled, will try to enable it and see if it solve the problem, in this case it could be helpful to note the quirk in the documentation.

No luck it seems that enabling the IPV6 did not solve the problem.
Could be the proxy?