Open Meetings + Kurento. Video and audio doesn't work

After numerous attempts to follow online documentation and configureation examples via forums we are not successfull in establishing video and audio conferencing with apache openmeetings/krento on Ubuntu 18.04 Server. When we try to work in LAN - all is ok, audio and video works. When we do login outside, web interface works good, but not works video and audio. We have opened all ports on firewall and configured 1:1 nat to server with open meetings/kurento. We try to configure stun/turn server Coturn on this server, but it doesn't change situation. Please advise if somebody able to assist. Thanks