eddy9:
if I try to send "Hi" to device 1 and "Hello" to device 2 and neither one is online, when one of the receiving devices comes online and it tries to send a new packet to it containing "What", it would send "HiHelloWhat".
You're saying that if you submit a packet to one device when it is offline, the shield will subsequently send that packet to a completely different device? That sounds horrendous, and I'd want to look for ways your experiment may have produced misleading results. Is each packet in that test definitely submitted to the shield by the normal sequence of begin packet, write data, end packet?
If you have time to test it with Wireshark or equivalent, I'd be interested to know whether the shield is sending one large UDP datagram containing all the buffered data (from all immediately preceding failed send attempts) or is sending each of the buffered packets in a separate datagram.