file sync not working with windows client

[KevinKlipsch]

Dear victoradrianjimenez,

I am trying to set-up a self-hosted zotero, using you repository. I got pretty far I think. It runs on a Ubuntu Server, and I am accessing it with the Zotero windows client.
I amended the necessary URLs to the resource/config.js in the zotero.jar for the client. myURL is of course my own server IP.
DOMAIN_NAME: 'myURL',
BASE_URI: 'http://myURL:8080/',
WWW_BASE_URL: 'http://myURL:8080/',
PROXY_AUTH_URL: '',
API_URL: 'http://myURL:8080/',
STREAMING_URL: 'ws://myURL:8081/',

Now, syncing of the bibliographic data works fine, for own and shared libraries.
What does not work is the file syncing of attached pdfs.
I found elsewhere, that changes also need to be made to \chrome\content\zotero\xpcom\storage\zfs.js
So I added at at the appropriate place, as suggested by https://github.com/foxsen/zotero-selfhost :

var url = params.url.replace(/http:\/\/localhost:8082/, 'http://myURL:4000');
params.url = url;

I used port 4000 here because this is what you stated for the S3 Web IU.
When trying to sync files, the zotero windows client tries for ages.
In the minio console, I can see that an object is created for my file. I can see a very small 13 kb .gz file in Minio, but when I download and open it, there is only one 0 kb file in the .gz, and not the (in this case ca. 1.5 MB pdf).
And when I try to sync from another user (who can access the same shared library), he will get the bibliographic info, but the attached file will not sync.
I also raised this here https://forums.zotero.org/discussion/114399/self-hosted-zotero-how-to-make-windows-client-use-it#latest

Are you able to help?