So there we are. I can in fact add users from a remote server but only if I add the IP.
# ldapadd -D 'cn=admin,dc=mydomain,dc=com' -x -f newuser.ldif -W Enter LDAP Password: ldap_bind: Can't contact LDAP server (-1)
# ldapadd -D 'cn=admin,dc=mydomain,dc=com' -x -f newuser.ldif -W -h 192.168.1.250 Enter LDAP Password: adding new entry "uid=JohnB,ou=users,dc=mydomain,dc=com"