(SOLVED) PDF Viewer - Can't Open PDF Files Error Message: NetworkError when attempting to fetch resource

When i’m open pdf files using local network, it can open perfectly.
not-error
But when I’m not on the local network, I can’t open the pdf files.

I use the https protocol on both networks. But only on the local network i can open the pdf file
What should I check first?

Nextcloud 21.0.2 Docker
Raspbian 10 armv7l

Error:
PDF.js v2.5.207 (build: 0974d6052)
Message: NetworkError when attempting to fetch resource.

(SOLVED). The reason I can’t open a pdf file is because of the idm extension. I remove the extension and BOOM, now i can open. Thanks to me