Issue: The server ID in the OpenVPN billing portal is showing incorrectly or unknown hostname.
Resolution: Change the hostname on your Access Server
Change Hostname Using hostnamectl Command
Almost all modern Linux distro comes with systemd an init system used in Linux distributions to bootstrap the user space and to manage system processes after booting.
Show your computer name:
Simply type hostnamectl:
Set or change your computer name
I am going to change ip-172-31-10-38 hostname to private-as:
$ hostnamectl set-hostname 'private-as'
Note: No need to reboot instance or restart Access Server service, since AS should pick it up as soon as it is changed, but just in case it did not, you can reboot your instance/server node or restart the OpenVPN Access Server service.
service openvpnas restart
You can check this link on how to do it if you are using other Linux Distributions.