RTP not transmitting over NAT

[I K]

Hi every one,
I'm new to Freeswitch and I'm having some difficulty configuring it, despite reading the documents. I have a Freeswitch running on a server with public IP and several Linphone android clients running behind NAT.How should I configure it to transfer audio and video and use ZRTP if one client is on a LAN behind NAT and the other client is using mobile data?!
Things I've acheived so far:1- bypass-media = false and proxy-media = false:In this mode audio works but when I turn on video no request is sent to the other phone. It other use just has to know when to turn on the camera to receive video. and of course ZRTP does not work well.
2-  bypass-media = false and proxy-media = true:audio works but video shows blank3- bypass-media = true and proxy-media = false:If both clients are on the same LAN everything works fine, but if one client connects via mobile data, they can still call each other but no media is transferred and the call is dropped after 30s.
I've been working on this scenario for over a week and I'm desperate to make it work. Thanks in advance for your help.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freeswitch.org/pipermail/freeswitch-users/attachments/20200215/800e3c71/attachment.html>