Hello to everyone!!
i have one question and i hope someone can help me!!!
I have Ubuntu Server LTS 18.04 with docker running and i need to map port 443 to 8123 but i can’t do that from my Router because i need to use a VPN with OpenVPN for obtain public IP.
I halso have duckdns running in Docker.
Thanks a lot
Stefano
For duckdns you can just map 8123 to 8123
@francisp
Thanks a lot for your reply 
The problem is that duckdns work correctly with 443 port and also i have received the certificate but i need (for alexa integration) to mpa port 8123 to 443 so when i access myip:443 with https i can access homeassistant
Ok, if I understand well, you first need to use OpenVPN to somewhere to get a public IP address ?
Yes, i have installed OpenVPN in my server, when OpenVPN will connect to the VPN server i have my public ip, then if i use this public ip with port i can access all my service but i don’t pass trought router because i use vpn so my ruter have xxx.xxx.xxx.xxxx public ip my server yyyy.yyyy.yyyy.yyyy.