Thanks @Blaise-93 – I didn’t know how the host header was getting set. I edited the Nginx config just how you said, but it didn’t quite work. It seems like it doubled up the host name so if I browse to any application url, I get this error from Django:
Exception Type: DisallowedHost at /farmyear/71
Exception Value: Invalid HTTP_HOST header: 'www.ifbt.farm,www.ifbt.farm'. The domain name provided is not valid according to RFC 1034/1035.
Raised during: main.views.FarmYearDetailView