In Digi TransPort WR44 (v1 and v2) there is an error executing Modbus commands (function code 06) when it is working to serial port.
An example:
Writing to device (Modbus/TCP -Modbus/RTU) - 00 00 00 00 00 06 01 06 00 08 00 AA
Device (Modbus/RTU) answers - 01 06 00 08 00 AA (88 77)
Digi WR44 answers with error (Modbus/TCP ) - 00 00 00 00 00 03 01 86 0B
Function codes 03 and 10 are executing without errors.
Problem exists also in the latest version of firmware.