Get the good IP in local machine

[eroamba]

Hello, thanks for your solution.I want to use in my local machine ubuntu .I read your tuto in youtube.But here
# set the external IP address or DNS name OVPN_HOST="udp://VPN.SERVERNAME.COM"
My local ip is 192.168.1.15 and dns is 192.168.1.1 .
Between the two, what should I put?
I tried to put both to test and I test on a window machine it doesn't work. My ubuntu must necessarily be on an online vps?
Thank you!