.htaccess does not handle HTTPS .well_known redirects properly, when running behind a reverse proxy

[gjoliver]

Steps to reproduce

1. Configure a reverse proxy in front of your Nextcloud installation for terminating HTTPS requests.
2. Use Chrome browser and go to Settings -> Overview page.
3. See the warnings about .well_known redirects not properly set up.

Expected behaviour

.htaccess should redirect to HTTPS URLs when x-forwarded-proto header is https.

Actual behaviour

Instead, .htaccess always redirect to HTTP urls today, since it doesn't respect the x-forwarded-proto header.

Server configuration

RancherOS
Custom Reverse Proxy
MariaDB, Redis
nextcloud:18.0.3-apache docker image, freshly install.
Chrome Browser

A working fix was proposed and shot down here: #22084
The PR thread contains tons of good context and discussion about the problem, and why I think it was the right fix.
Hopefully useful if anyone wants to pick this issue up.

[szaimen]

Hi, please make sure that your reverse proxy configuration is correct.
https://docs.nextcloud.com/server/stable/admin_manual/configuration_server/reverse_proxy_configuration.html?highlight=reverse%20proxy