HOWTO : Configure OpenVPN on Ubuntu 16.04

There is a very good article by Digital Ocean for setting up OpenVPN on Ubuntu 16.04. After the above setup, you are required to further configure it to make it working properly.

The following additional settings is to allow all VPN clients can use the same certificate to login the VPN server. Meanwhile, it also allow the maximum concurrent users to 100.

sudo nano /etc/openvpn/server.conf

Uncomment (remove ";") the following :

duplicate-cn

max-clients 100

That's all! See you.