Nick,
On the message that failed you timed out between the receipt of a single byte (start of the mlp encapsulation) until the rest of the message.
The timeout is at 15 seconds so that is a long time for delivery of portions of a message.
I might suspect there is a problem with the sending system or perhaps the network in between.
Jim Kosloskey
email: jim.kosloskey@jim-kosloskey.com 29+ years Cloverleaf, 59 years IT - old fart.