 <p>Per @datenwolf's answer, you simply can't send more than 64k in a single UDP datagram, as that limit is implicit in the two-byte length field in the protocol.</p> <p>Furthermore, it's not actually a good idea to send even that much at once. You should limit your packets to the MTU on the path between the two ends (typically in the region of 1500 bytes or less) so that you don't get <em>fragmentation</em> in the IP layer.</p> <p>Fragmentation is bad - ok?</p>