hi, i'm also having the same issue, same setup, but instead of private IP i have real IP on my WAN interface. and regardless that i've used

rtpproxy_manage("coeir")

and

rtpproxy_manage("coier")

kamailio is still replying with my internal (sip+rtp) ip in the outgoing to WAN SDP.

Can you please help to understand how do i need to manager rtp proxy to send WAN IP in SDP? when my WAN IP is private IP and my carrier is also having private IP from same network, the issue is not seen.

Thanks in advance,