At connection on openvpn to the client beats off connection. Why?

Question

openvpn

Trouble happened .
Linux Debian 9 with Guacamole + Apache TomCat8 installed, OpenVPN server is installed on the same machine (CA server is installed on a separate machine).
I create a server > client connection using the visual part of Guacamole with tunnel forwarding through OpenVPN.
All the necessary components for VNC and VPN are installed on the client and on the server.
-- LAN connection option using Guacamole + VNC + OpenVPN for a secure connection, everything works.
-- The variant with the connection behind NaT beats off the connection, but both the first and the second variant, the ip-address of the forwarded connection is pinged from the server and the client.
How to solve this problem?