UDP is connectionless, but like all stateful network devices, BIG-IP creates connections for UDP. Idle UDP connections eventually expire. As I said earlier, you can only select the pool (or pool member or server) and SNAT once at the beginning of the connection. You can not change the server or SNAT after the connection to the server is established. However, if you enable the datagram lb option in the UDP profile, then a new connection will be established for each packet. This allows you to choose the pool and/or SNAT for each packet. Use the CLIENT_ACCEPTED event. Good luck!
Nimbostratus