By default, Django will assume that your root URL is the root (/) of your domain.
Using a reverse proxy, we can run multiple django instances on the same server, using the same domain. (http://server.org/site1/, http://server.org/site2/, ...)
Many redirects of your application will then be broken (most notable is validation of login form). You can fix that by forcing the root URL in your settings
FORCE_SCRIPT_NAME = '/site1'
If you use Sentry, you'll also have to set
SENTRY_URL_PREFIX = '/site1'