Configuration problems, reverse proxy and Office

I also keep getting the following errors in php_errors.log:

[06-Jan-2025 09:17:14 UTC] PHP Warning: file_get_contents(http://localhost:9983/hosting/capabilities): Failed to open stream: HTTP request failed! in /var/snap/nextcloud/45728/nextcloud/extra-apps/richdocumentscode/proxy.php on line 268
[06-Jan-2025 09:17:14 UTC] Old server found, restarting. Expected hash a but found b.

and the following in nextcloud.log:

“app”:“richdocuments”,“method”:“GET”,“url”:“/index.php/apps/richdocuments/settings/check”,“message”:“cURL error 3: malformed (see libcurl - Error Codes) for /hosting/discovery”

Are these somehow related to this problem? Are these URLs OK?

And for the record, editing office files doesn’t work properly in web browsers on any client (Firefox on Linux-laptop, Firefox on Android, Safari on iOS) either, so this doesn’t seem to be a client specific issue.