Bigblubutton behind NAT. Freeswitch works externally but doesn't work correctly internally. How to fix?

Question

FreeSWITCH

Good afternoon.
Installed according to the official Bigbluebutton documentation.
Further, according to the official documentation, I configured it to work behind NAT.

Now the situation is such that users from the Internet can use the BBB, a conference is created, echo tests are passed, etc.
Users within the network cannot work. Echo tests do not pass, they can only listen.

The network scheme is as follows (all ip for example):
192.168.100.0/24 - users within the network
192.168.200.20 - BBB server in the DMZ network
50.140.23.27 - external ip for BBB.

192.168.100.0/24 (internal users) > firewall > 192.168.200.20 < firewall < 50.140.23.27 < external users
Everyone needs ports open everywhere.

The problem is that internal users (according to about: webrtc in Firefox) for some reason still try to cling to an external ip, although they should on an internal one. Therefore, the echo test, etc., does not pass.

Has anyone come across? How to decide? thanks in advance