Register Extension and Gateway over OVPN

Hi every budy
i installed Vital PBX on Digital ocean, i ainstalled Open vpn addon, the connexion from my PC and from compaatible gateway is ok but am still unable to register extension from my computer to the VPN adress and also not able to register the media (FXO) Gateway to this adresse,
but the web interface is accessible from this adress from the browser
can some one help me resolve this issue ?

Thank you in advance