I want to forward certain ports on VPS via OpenVPN. I have installed the OpenVPN on my server and it works great but I was not able to forward port. It seems Google Cloud's VPS servers are behind NAT. So there is an internet facing ip address and also an internal ip address. Therefore, when I try to forward ports from external ip to OpenVPN's internal ip (10.x.x.x), it does not work because server is behind NAT and there is an internal ip. Is there a way to forward ports in this situation?