Total general observation and honest question, but how do you balance advocating privacy and security when you block access to your help site while on a very reputable VPN? 
How do you know that Nextcloud is denying access to the help site using a VPN?
What is the exact url you are entering in the browser and which is the exact error message being displayed when you try to access the site using a VPN?
You can e.g. access the website using TOR browser without any problems.