The AS400 commonly uses terminal emulation from TN family (TN3270, TN5250, or similar). This is not supported by Rebex Terminal Emulation library. Only VT family is supported (and couple other terminal emulators in experimental mode). For complete list please visit Standards and platforms page.
The VT family terminals do not have any option for Workstation ID as far as we know. If you point us to a specification for this option (what should be sent to the remote host) we can assist you in solving this issue.
The TerminalOptions.TerminalName is used to negotiate terminal type with the remote host.
In more details:
When connecting with SSH, the value of
TerminalOptions.TerminalNameis sent in theSSH_MSG_CHANNEL_REQUESTpacket when requesting pseudo terminal (see RFC4254). Default value isxterm. If the value isstring.Emptyan empty terminal name is sent to the remote host.When connecting with TELNET, the value of
TerminalOptions.TerminalNameis sent when negotiatingTerminal Typetelnet option (see RFC1091). Default isxterm. If the value isstring.EmptytheDEC-VT100is sent for terminal type.
I don't think the TerminalOptions.TerminalName is related to Workstation ID. Because we do not send any Workstation ID (we do not know how) it seems that the Rebex Terminal is not compatible with your AS400. Please make sure the Rebex Terminal can really work with your AS400.
Actually, how do you know that the issue is related to the Workstation ID? Did you get any related error?