Grandstream gxp1610 always replace inner ip address to public


Hello everyone. Please tell me why i get public address from my phone connected over vpn?
Phone settings -> NAT Traversal NO ( phone show nat status - unknown nat ).

I have 2 networks and connected over openvpn
All devices from work over vpn exept grandstream phones. I sure i dont have any problem with routes or networks, because i tested it with tcpdump and telnet ( all devices connected with inner ip’s)
I think phone has special settings which replace inner address to public, but i discouraged which one.


I disable SIP ALG on my router and many times reboot phone -> it give me good result. thanks all