WIZ750SR control DTR signal

I need stuffs for controlling some device with serial signals (with modem signals too!) via ethernet.
I’ve bought a WIZ750SR-TTL module because according to the documents it can control RTS/DTR signals.
My WIZ750 configured as TCP server with status pins set as DTR/DSR and protocol is RFC2217.
When I toggle RTS signal with terminal programs, it seems in wireshark monitor to send packets to WIZ750 device , but physically not any changing on WIZ RTS pin. If this pin is configured as PHY link, it works normally. But does not work when configured as DTR signal.

How do I have to configure for this to work?