To change the VPN server - navigate to:

http://admin.hiddenrouter.com/cgi-bin/luci/admin/network/network/HiddenRouterVPN (or http://10.10.10.1/cgi-bin/luci/admin/network/network/HiddenRouterVPN ) and replace Endpoint Host under peers with your desired server.
Press "Save and Apply" (always use "Save and Apply" when editing anything) and then to make sure that it switches to the new server - press the restart button at the front of the router, left side button.

And you are set!

To get a list of available servers - please contact us by opening a ticket here.