I currently investigate about Nextcloud as a potential solution for sharing files between several physical sites of an association. As a current Owncloud home user, I have some knowledge about this kind of solution, but I am no expert.
Several users, located on site A or site B, may simultaneously access to the same file (mainly spreadsheet files, using Excel), possibly for applying changes to it. Simultaneous changes shall not lead to losing data changes made by any user. We therefore need either a solution that allows users to make changes simultaneously (~Google Sheets) or at least a solution that notifies user2 that user1 already uses the file.
Combining Nextcloud Server, Nextcloud Sync and Collabora seems appealing. I currently try to setup a VM for testing that solution, but for the moment I failed. Maybe because my server is a VM on my intranet, and I have no true SSL certificate.
Does someone know whether I can expect the upper solution (Nextcloud+Collabora+Sync client) to be satisfying regarding the simultaneous file changes problem?