The configuration is the following:
This is then connected to a serial device, that is configured as 9600 8,n,1.
We have a serial diagnostic board in the path with LED lights that flash when there is traffic. When the device connected to the Teltonika device transmits any data, it is received by the Teltonika, and transmitted back to the serial device, but is not passed to the tcp sessions as expected.
Likewise any traffic that is received in the tcp session is not passed to the serial port.