Due to the general complexity of networking software and the many different NAS models that QNAP offers, it’s often difficult to identify the cause of a given problem. However, you can do a few things that will take care of the most common issues.
The most common mistake is entering a VPN username or password incorrectly. As a result, this is the first thing you should check.
Upgrade to the latest firmware for your device, and while you’re at it, check for QVPN updates too, since some VPNs won’t work with the original version.
Try importing the OVPN file for a few different servers in turn. This should give you an idea of whether the problem is with you or your VPN provider.
If all else fails, contact your VPN’s customer support team. They deal with similar problems every day and should be able to give you more in-depth advice.