Digi One IAP two ip connection for the same time

I have Siemens S5 (3964R) connected to a DigiOne which is the converte/bridge to TCP/IP-Ethernet. We tried to connect from two different IP-adresses (OEE1 and OEE2) for the same time to collect production datas, but it doesn’t work. It is either only one or the other connection is possible. We would to like to have both connections. How do I have to set up the DigiOne to have both connection for the same time?
Current Version of DigiOne IAP: Version 82000770_G 04/04/2007

No, as a generic ‘terminal/device server’ cannot understand how to mix 2 client-server conversations.

The DOIAP can do this for Modbus or Rockwell, as it understands what is a request & the matching answer. So like a print server, it can juggle the 2 conversations at once.

For your S5, I’m assuming this is MPI (or whatever the serial encap of MPI is called), and the DOIAP has no built in intelligence to understand how to safely let two clients mix their traffic.