Onlyoffice and Document-Server - Document blocked by Content Security Policy

I have today installed the OnlyOffice and Document_Server app. So far everything worked out. But if I want to open a document e.g. docx, I get the error

Onlyoffice is currently not available. Please contact your administrator

and in the console I get two warnings

1. Content Security Policy: The settings of the page have the loading of a Resource blocked to eval ("script-src"). global.js
2. The resource of "" was because of a MIME type conflict ("text / HTML ") blocked (x-content type options: nosniff).

Unfortunately, I did not find a solution for many hours of Google.

Many greetings