Our testingteam created a howto for such a situation. Have a look here and see if it is usefull for you: http://community.nethserver.org/t/setup-muliple-site-office-with-point-to-point-ipsec-vpn-and-separate-dc/1693
Also keep in mind that both subnets must be different: http://dev.nethserver.org/issues/2857 (this is not an issue with your situation because you already created different subnets)