Most failed Nextcloud plus OnlyOffice setups are not broken - they are starved. One honest sizing page saves the whole project.
Before you install anything, size the server honestly. OnlyOffice Docs is the heavy half of this pair, and its published floor of 4 GB RAM surprises people who expected a light add-on. This page gives the real numbers for both services and the simple one-box rule for small teams.
OnlyOffice publishes its own minimums for the Docs server: a dual core 2 GHz or better processor, at least 4 GB of RAM and around 40 GB of free disk for the program itself. Treat that 4 GB as the floor for the Docs service alone - not for the whole machine. When RAM runs out mid-editing, the symptom is editors freezing or documents failing to open, and people blame the network.
CPU matters less than RAM for small teams. Two to four cores handle a small office comfortably because most editing work is light; heavy simultaneous spreadsheet work is what pushes CPU up.
Nextcloud is lighter: the server software runs in about 512 MB per PHP process, and a small install is happy with 1 to 2 GB for the web side plus the database. Use MariaDB or PostgreSQL rather than SQLite once more than one or two people use it - SQLite becomes the bottleneck very quickly.
Storage for Nextcloud is simply your files plus headroom. Plan the data disk for the files you have today, the versions and trash Nextcloud keeps, and at least a year of growth - running a file server at 95 percent full is asking for sync errors.
Documents take 20 plus seconds to open, the editor disconnects during long sessions, or the server swaps heavily during office hours. Check with free -h and top while people are actually editing - sizing problems only show under real load, never on an empty Sunday test.
Watch the video to see the class of machine the full setup runs on, then size your own server with this page.
Watch Full VideoIt may install and even open a document, but under real use it will swap, editors will stall and saves can fail. The published minimum of 4 GB is for the OnlyOffice Docs service alone. For a combined server, treat 6 GB as the tight floor and 8 GB as the sensible plan.
A 4 core, 8 GB server comfortably serves a small office where a handful of people edit at the same moment and the rest sync files. There is no magic user number - simultaneous editors and big spreadsheet work decide the load, not total accounts.
The file store can live on normal disks, but the system, the database and the Docs cache belong on SSD. Document open speed and editor smoothness improve far more from an SSD than from extra CPU cores.