A lot of information in your post is missing, such as :
versions of both OSes, exact command line parameters, errors returned, how did you setup the FQDN, what are the DNS servers for those two machines, can they see each other, can the FreeBSD ping the windows, does the ping by IP address succeeds, can you ping the FreeBSD machine from other machine in this network segment or out if it, what kind of IP address has the FreeBSD machine - public or private, are there any firewalls, and so on.