sftp_list unable to connect

I am using sftp_list with sftp_download to sync files from a server to my local storage.

I’m getting Failed to connect to IP_ADDRESS; waiting 15 seconds before retrying.

any idea on my config?

config.yml:

variables: variables.yml

tasks:
  serversync:
    sftp_list:
      host: '{? sftp.host ?}'
      username: '{? sftp.username ?}'
      private_key: '{? sftp.private_key ?}'
      private_key_pass: '{? sftp.private_key_pass ?}'
      dirs:
        - '/path/folder'
    accept_all: yes
    sftp_download:
      to: '/mnt/path/downloads'
    notify:
      entries:
        title: 'FlexGet'
        message: 'Downloaded {{title}}'
        via:
          - pushbullet:
              api_key: '{? pushbullet.apikey ?}'

schedules:
  - tasks: serversync
    interval:
      minutes: 30

variables.yml:

sftp:
  host: 'ip address'
  username: 'user'
  private_key: 'path/file'
  private_key_pass: 'pass'

pushbullet:
  apikey: 'key'

this is running on a raspberry pi 3. I made sure to install pysftp 0.2.8 since I ran into this on a windows box as well. back then I had issues with the ssh pub key format (had to convert from putty to openssh format). tried the same thing and also tried generating new keys and adding to authorized_keys on the server but still no luck.

if no fix or workaround is doable, is there any other plugin or application that can do the same thing I want? use flexget to check entries and then something to download the files. not very much documentation on the wiki other than the options for sftp_list