[SR-Users] register fails from openvpn clients

I have kamailio 4.1.0 running on a server on a real ip and behind a firewall. NAT detection is enabled on kamailio because many remote clients are behind NAT, so NAT is working fine along with rtpproxy. Everything else (incoming, outgoing) is working fine except the following: Users who are connected to our openvpn server (bridged mode) which is on the same subnet with kamailio, fail to register. I suspect that kamailio detects NAT on these clients as all of them are behind NAT, but they also have obtained a real ip from our openvpn server on their tap interface and as a result, REGISTER fails. One solution, but not the best is to exclude kamailio from our openvpn routes but I would not prefer this because I wil not be able to manage the server remotely My config: http://pastebin.com/JSxzgmKH Any suggestions?