I have setup nextcloud on CasaOS and cannot get it to open any documents inside of nextcloud. Any ideas on where to start?
hi @RomanNum3ral welcome to the forum 
as always I would start with the docs search through existing posts. e.g. Collabora integration guide
sharing you installation details and logs helps others to understand your problem.
Here is the log. Not sure what would cause this:
ClientException Client error: POST http:/MYDOMAIN/apps/documentserver_community/ConvertService.ashx resulted in a 405 Method Not Allowed response
getConvertedUri: from ods to jpeg
It is also stuck on the “Use your own server” option and will not let me switch to the built in code option