curl --request POST \
  --url https://demo.onlinebillingform.com/api/v1/vpn/servers/update \
  --header 'Content-Type: application/x-www-form-urlencoded' \
  --header 'token: <api-key>' \
  --data id=123 \
  --data 'server_name=<string>' \
  --data 'ip_address=<string>' \
  --data ssh_port=123 \
  --data 'ssh_password=<string>' \
  --data 'ssh_username=<string>' \
  --data max_connection=123 \
  --data country_id=123 \
  --data 'vpn_type=<string>' \
  --data 'ssh_password_current=<string>'

{
  "success": true,
  "message": "Server: 8 updated successfully"
}