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When using the Cura OctoPrint plugin (GitHub/Ultimaker) I found that my Authentik proxy in front of OctoPrint was returning 404 errors, despite allowing \/api\/.*.


After four hours of debugging, I found the reason was that the way the Qt network library that Cura uses works, it made Authentik think the requests were coming from a different hostname by including the port number and therefore not match any known proxy providers.

When using the OctoPrint web UI and using other tools like curl, the hostname would register as, however Qt would make it appear as The fix was to setup a duplicate proxy provider and application in Authentik with the port number as part of the hostname.

Duplicate proxy provider in Authentik.

Now the OctoPrint web UI and Cura all work correctly with extra authentication.

It seems most tools and web browsers automatically strip the ports 80 or 443 from the hostname when using http:// or https://, respectively, but I guess Qt just has to be different.