Errors when co-editing online (via Nextcloud): Cannot open files / Internet connection restored

We use Nextcloud in combination with Only Office to edit documents online. Recently, two problems have been occurring when documents are opened via Nextcloud in the browser and are edited in the Only Office editor:

Firstly, some members of our team have the problem that some documents cannot be opened. The following error message appears: “An error occurred while opening the file”.


On the other hand, there is the error message “The internet connection has been restored and the file version has been changed.”


This always occurs when a document has been opened online in Nextcloud via Only Office, but you have not edited it for a while or the device was in standby mode. After refreshing the page, the message no longer appears and everything works again.

Unfortunately, even after intensive internet research, we were not able to find out how to solve these two problems.

Do they also occur with others, and are you aware of any possible solutions?

Many thanks in advance for your help!

Kind regards

OS: Mac & Windows
Browser version: Firefox, Safari, Google Chrome