Advice on LS300 Serial configuration


After a successful login to the ACEmanager though 3G network, I’m trying to configure the serial forwarding.
The current configuration I have is as follow:

The third party software that connects to the serial device is giving me this king error:
ERRWX : Inactivity timeout of the network port

When I use the third party software directly with the serial port, it works well.
So i suspect my serial configuration to be wrong, any idea of the messing part?