The current protocol for the mesh serial interface as documented here:
has an issue when using it for subscriptions to mesh messages which are segmented. When a segmented message whose total size is greater than 235 bytes is recieved, any data past byte 235 is lost. (384 bytes are possible with a segmented messaged which includes the transmic and opcode).
I believe this is the result of the length field of the serial packet being represented by a single byte. The internal serial packet struct uses a 16-bit variable to store the length byte when the packet is serialized it gets clipped to 8-bit.
I am looking at modifying the code to support full length segmented messages. This is just a heads up for others who may be using the serial interface firmware and segmented messages.