Owncloud Error while downloading the document file to be converted

Hi! I just got a problem. I try to integrate onlyoffice docs with owncloud. But when I configure the onlyoffice connector i get an error: Error while downloading the document file to be converted.
Document Server version: 7.4.0.163
Type of installation of the Document Server deb/rpm
OS: Ubuntu 18.04
Owncloud 10.3.2

Hello @rahmo
Please let us know connector app version. Additionally please reproduce the situation (make a screenshot of the error on the connector page) and provide us with whole Document server logs folder. It’s located here:
docker: /app/onlyoffice/DocumentServer/logs/documentserver/
deb\rpm: /var/log/onlyoffice/documentserver/
Windows: Program Files\ONLYOFFICE\DocumentServer\log

Hi! The connector app version is 7.8.1.

Thank you for you update. Please reproduce the situation and provide us with whole Document server logs folder. You can upload them to any external storage and provide us with download link.
If logs contain sensitive data, you can contact me directly (private messages).

[2023-07-03T10:41:24.433] [ERROR] [localhost] [conv_check_1561059344_docx] [userId] nodeJS - error downloadFile:url=http://your_ownCloud_server/index.php/apps/onlyoffice/empty?doc=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJhY3Rpb24iOiJlbXB0eSJ9.BybCafCB-rx79l7iOnzRThSNIxSDY-49p_gR2LX63zk;attempt=3;code:undefined;connect:undefined Error: Error response: statusCode:403

Thank you for provided logs. It seems that Document server can’t download a file from your ownCloud server. Are there any error lines in ownCloud logs?
Also please check out mutual availability between servers. Go to Document server and run wget https://domain_name_of_ownCloud. And vice versa, from ownCloud server run wget https://domain_name_of_Document server.
Please show us the result.