OnlyOffice Thumbnail Creation throws a lot of errors (NC 22.1.1)

Hi,
i am using onlyoffice-documentserver on Debian. Opening documents works as it should.
I have enabled “Use OnlyOffice to generate thumbnails” in Admin settings.

When i now run sometimes the creation for thumbnails via the preview-generator with:

su -m www -c 'php /usr/local/www/nextcloud/occ -vvv preview:generate-all'

Nextcloud generates a lot of errors for office documents with the following error:

Exception: Error occurred in the document service: Error while downloading the document file to be converted.

but the thumbnail gets created.

Furthermore the creation for the thumbnails looks like this:

'enabledPreviewProviders' => 
  array (
    0 => 'OC\\Preview\\TXT',
    1 => 'OC\\Preview\\MarkDown',
    2 => 'OC\\Preview\\OpenDocument',
    3 => 'OC\\Preview\\PDF',
    4 => 'OC\\Preview\\MSOffice2003',
    5 => 'OC\\Preview\\MSOfficeDoc',
    6 => 'OC\\Preview\\Image',
    7 => 'OC\\Preview\\Photoshop',
    8 => 'OC\\Preview\\TIFF',
    9 => 'OC\\Preview\\SVG',
    10 => 'OC\\Preview\\Font',
    11 => 'OC\\Preview\\MP3',
    12 => 'OC\\Preview\\Movie',
    13 => 'OC\\Preview\\MKV',
    14 => 'OC\\Preview\\MP4',
    15 => 'OC\\Preview\\AVI',
    16 => 'OC\\Preview\\M2TS',
  ),

Anyone perhaps knows, how to solve this?

Thank you!