I can report that the solution provided by Archie has been working fine since January, I just had to use two adapters (one Net-Eni and one RTA-Eni) to balance the connections load.
I am using the AB Net-Eni with the Ingear drivers to communicate the .NET app we use for data collection with a database, and the RTA-ENI for all the other devices (PC as HMI with factory talk and another app with AHMI, programming interfase, RFID badge reader through Ethernet/Ip to TCP gateway).
Update AHMI to latest beta version, as Archie said. Provide more details on what devices/drivers are you trying to connect through RTA-ENI.