Thank you very much for reply and the possible solution, I shall trial this over the next few days.
I have found the following definitions in the C SDK (twDefaultSettings.h) so I'll go ahead and change these to be larger.
* \brief The maximum size of a complete message whether it is broken up as a
* multipart message or not. Messages larger than this will be rejected.
* Measured in Bytes.
#define MAX_MESSAGE_SIZE 16384
* \brief The maximum size of a message chunk. Messages large than this will
* be broken up into a multipart message. Measured in Bytes. This value
* should be the same as the server side configuration which defaults to 8192.
#define MESSAGE_CHUNK_SIZE 8192
Do you know where on the server you change the MESSAGE_CHUNK_SIZE?