hi, sounds like your server has firewall on it - so whilst the daemon is listening locally, the firewall is rejecting the packets (that'd be the cause of the ICMP unreachable)..... add UDP 1812,1813 and 1814 to the firewall config... on redhat - /etc/sysconfig/iptables or use a GUI tool
alternatively, the AP cannot actually reach the server because of other reasons - network topology, router/switch ACLs etc - i dont know your network alan - List info/subscribe/unsubscribe? See http://www.freeradius.org/list/users.html
