Hi there Pabar - and anyone else reading this forum.
In response to:
“Also, I do not see my network shared folders when I open a document from OnlyOffice”
In my case this was due to OnlyOffice being installed as a Flatpak and hence in a sandboxed environment.
In this case, uninstall OnlyOffice via the Software Centre/similar and then install again in this way:
And, if you are on a Ubuntu/Debian based distro like either download the .deb package and install or follow the instructions at the following web address to add the OnlyOffice repository to your package manager (recommended)
Hope this helps!