Settings - Network - Incoming Ports
The TCP port used for incoming connections and UDP port for incoming DHT packets can be adjusting by clicking on the respective buttons. For more information about selecting a TCP port, go to the Incoming TCP Port Selection Window page. For more information about selecting a UDP port for DHT, go to the DHT Incoming UDP Port Selection page.
Refer to steps 2 and 3 in the Optimizing Tixati Guide for more information about receiving incoming connections and UDP messages for DHT.