In a passive node connection, dlt-daemon gateway transmits the TCP segmentation message.

I am using the dlt-daemon 2.18.10.

The dlt-daemon operating on the QNX target and two gateways configures theusing AUTOSAR based ECU node and another Android dlt-daemon.

Below the configuration configured in QNX

[PassiveNode1] -> Android DLT gateway configuration
IPaddress=x.x.x.x
Port=3490
EcuID=ANDR
Connect=OnStartup
Timeout=10
SendControl=0x03,0x04,0x13
SendSerialHeader=0
SendPeriodicControl=0x03:5,0x13:1

[PassiveNode2] -> Autosar DLT gateway configuration
IPaddress=x.x.x.x
Port=3490
EcuID=ECUA
Connect=OnStartup
Timeout=10
SendControl=0x03,0x04,0x13
SendSerialHeader=0
SendPeriodicControl=0x03:5,0x13:1

Problem:
1. Any request to the dlt-control command line example adjusting the log level to all the passive node messages is going through segmentation (Header + Payload), and Autosar is not supporting TCP segmentation.
2. If we control from the DLT-viewer, the DLT-gateway daemon sends the to all PassiveNode message, which is going through segmentation (Header + Payload).

Note:
I observed the two syscalls calling when I debugged the dlt-client lib function dlt_client_send_ctrl_msg.

ret = (int) write(client->sock, msg.headerbuffer + sizeof(DltStorageHeader), msg.headersize - sizeof(DltStorageHeader));
ret = (int) write(client->sock, msg.databuffer, msg.datasize);

What is the use of two syscalls in the dlt-client lib?
Why will dlt lib send header and data packets separately? Is there any limitation in Linux or QNX?