At our company we have been using Nextcloud plus the integration app with OnlyOffice Docs Community Edition for quite some time without problem. As part of our plan to make services more reliable we’re moving towards a high availability architecture.
In regards to OnlyOffice we opted for 3 servers running Nginx + Docs and another 3 servers running Redis, MariaDB and RabbitMQ to lessen the load on Docs servers . These services are clustered and are able to communicate with their counterpart in the other servers.
When it comes to concurrent editing of documents users can’t see each other unless the balancer sends them to the same backend server. After much digging I found this post: Opening new doc failed in ds-example - #4 by Alexandre which mentions Community Edition doesn’t make use of Redis. Is this actually correct? We used the install script provided in Installing ONLYOFFICE Docs using the provided script - ONLYOFFICE (without Docker, just using deb packages), and Redis is mentioned in the default.json configuration file.