The best option for you is to Uninstall and install and Configure the platform your interfacing AS400 to. that has worked for me in the past. It will depend on what model AS400 server your attempting to access.
The discussions below should be taken as the answer. The answer text above has essentially nothing to do with the question and is almost totally inappropriate. To interface an AS/400 with Windows or Linux, use the same facilities that Linux and Windows use to interface with each other.
The question is far too vague to give a specific answer. All anyone can say is to use whatever protocol you’re comfortable with that works for both Linux and Windows. The discussions list a variety of possibilities.