This dont look right:

<TRioUnitControlThread (/172.16.xxxx): Rio has accepted <connection. Interface: / 172.16.xxxx
sending Query query: http://67.65.154.xxx:12078/query?artist=

This is indicating that the reciever is 172.16.xxxx? but the server is on 67.65.154.xxx?

First rule, keep it simple. The ARM dishes out the ip addresses, make sure you have no other DHCP server active, if using a static address for the Server PC with ARM/TRIO on it (67.65.154.xxx) then set the ARM server to allocated ip addresses in this range as well. SAre the MP3's also on the same PC as the Server?