Document saving and download sometimes fail


I’m having an issue with the OnlyOffice Document Server integration that is driving me crazy. Everything looks to be working fine, but sometimes when editing any file with OnlyOffice, the saving and downloading crash.

I can create an edit a file just fine, it will work perfectly, but randomly the auto and manual saving will crash and I’ll lose all modifications, it just wont save, nothing will happen… not even an error. When this happens, I can’t download the file either.

It’s happening very often, and I don’t know what to do!

My configuration is:

Nextcloud 15.0.4 (it’s behind a proxy and inbound connections are served by a reverse proxy). Added the certificate to the OnlyOffice VM. Running Ubuntu 16.04.5 LTS
OnlyOffice Document Server, same as Nextcloud server. Running Ubuntu 16.04.6 LTS
Reverse proxy: Squid running on pfSense. External certifcates are handled by the Reverse Proxy with LetsEncrypt. Internal certificates are self signed.

Document Server config within Nextcloud:

Document Editing Service address: https://my.external.domain
Document Editing Service address for internal requests from the server: (the internal IP of the Document Server)
Server address for internal requests from the Document Editing Service: (the internal IP of the Nextcloud Server)

Secret key (leave blank to disable): blank

This configuration validates successfully.

I can make it fail pretty quickly… If i press delete continuously on a spreadsheet it will eventually crap out.

Any ideas?