The mDNS domain suffix is .local, and the freedombox-setup package does not ship an avahi http.service to advertise something like _http._tcp.
See: https://github.com/petterreinholdtsen/freedombox-setup/tree/master/avahi-services A possible /etc/avahi-services/http.service might be: <?xml version="1.0" standalone='no'?><!--*-nxml-*--> <!DOCTYPE service-group SYSTEM "avahi-service.dtd"> <service-group> <name replace-wildcards="yes">%h</name> <service> <type>_http._tcp</type> <port>80</port> </service> </service-group> You could try to see if adding the XML and navigating to http://freedombox.local works.
