'GetConvertedUri on check Error' and 'Download Empty without jwt' when connecting onlyoffice to nextcloud 14

I am running nextcloud and onlyoffice behind an nginx reverse proxy which does TLS termination.

I did manage to get some connectivity between my running document server and my nextcloud.

I (believe to have) configured JWT according to this post: *

Also i configured nextcloud to not verify onlyoffice like this: OnlyOffice Integration https certificate failed - #2 by Reiner_Nippes

And did the same for onlyoffice like this: Can't connect Nextcloud 13.5 to onlyoffice - #4 by Frankenstein

Disabling verification really scares me, but still “Error when trying to connect (Error occurred in the document service: Error while downloading the document file to be converted.)” appears.

It gets even scarier, as the error log shows curl errors with (almost) completely random urls as seen in the picture below. The eff/startpage urls may come from some weird browser interaction (search engine + https everywhere) but i can not explain any of the other things (edri???).

Does anyone have an idea?

Those URLs are part of a internal connection check.

Awesome, i found out, that i accidentially forwarded every port 443 request to the reverseproxy. Thanks for the hint!

The connection problem with jwt and GetConvertedUri still persists. I originally thought they were connected to the ceritficate issues, but they do not seem to be.