Nginx on TN Scale through Xfinity router

[mitzaotomitza]

Is there any way to configure Nginx and Cloudflare when dealing with Xfinity router? I have the XB8 Xfinity router and can't change almost anything on router configuration page ( most of the settings are greyed out).
I just need to setup Nextcloud and Plex in a safe way. Any ideas or links to a good solution would be much appreciated.