Yes, only one traffic stream should be enough, but I have no idea how to implement it. I’ll research about this.
Thank you very much for analysing my configuration, I appreciate your help!
I found the problem. It was missing a masquerade NAT rule. I added to the WAN interface list (that already have a masquerade rule in place) the ether3 interface, that ether3 connect to the OpenVPN router LAN:
/interface
list member add list=WAN interface=ether3
Everything is ok now, thank you all!
Regards,
Rodrigo.