How to make friends WebRTC calls via verto for Freeswitch with NAT?

Question

FreeSWITCH

I'm trying to set up calls via the web (Verto Communicator).
There is a server with a public IP, virtual machines are spinning on it.
The task is to place Freeswitch on a virtual machine, so that calls via WebRTC work.
If Freeswitch is placed on the server itself (with a real IP), calls via WebRTC naturally work.
As soon as Freeswitch is placed in the virtual machine, the call goes on, but there is no sound in both directions.
I have already tried all possible combinations of NAT settings .. it does not work.
At the same time, if you connect with a regular softphone via SIP (5060 is forwarded to a virtual machine) - calls go, there is sound.
Tell me where to dig?