You are trying to register a newly deployed Disaster Recovery VPN Appliance and get this error message:
[The command fas failed. HTTP 404: Got unexpected response code  from ADRC service at [https://us-cloud.acronis.com/api/dr/v1/vpn/aapliance].]
You are registering the VPN appliance with a Partner administrator account, which is not supposed to be using backup and DR services. Please use the company administrator account for registering the appliance. The difference between a Partner and a Customer tenants (account) is described here.