I have Nextcloud and Onlyoffice installed through TrueCharts on my TrueNas server. When both my Nextcloud and Onlyoffice are booted, by default when opening a Onlyoffice compatible document and editing it in the browser, will result in an error messsage:
When you login with an administrator account, navigate to Administration Settings, OnlyOffice > All the settings here are correct. When clicking save, nothing changes other than receiving the message that the connection was successful.
After this saving works flawlessly until the Nextcloud container has been rebooted. After that the same actions need to be performed again.