IO Server Processes Failing with Dual NIC

Dual NICs are normally used for network load balancing or redundancy. Have a look at Automatic Metric in your NICs' Advanced TCP/IP settings in Windows. In general, for load balancing applications, Automatic Metric should be selected (and Windows will do it automatically) while for redundancy, you should manually set the priority of NICs where a lower number stands for a higher priority). Normally, dual NICs should be in the same subnet for load balancing.

It appears that your application is for network redundancy. So you need to manually set up SCADA NIC in a higher priority in Windows. Questions for you

• Are machine names are used in Network Addresses in your SCADA project?
• If not, are IP addresses Static
• Are you using Encrypted Mode at runtime?

Not quite, the dual NIC is just for the Citect connector to talk to the historian seating in the corp network

• IP Addresses Used
• IP Address are static
• Mixed Mode

Are you set up like this?  192.168.215.xxx is the SCADA network. 192.168.15.xxx is the corporate network.

Yes, but SCADA is 192.XXX.XXX.XXX and CORP is 10.XXX.XXX.XXX

Yes, but SCADA is 192.XXX.XXX.XXX and CORP is 10.XXX.XXX.XXX

In that case, the problem seems to be in the connector configuration. It is expected that the Citect Connector for SCADA connection should be configured with 192.XXX.XXX.XXX while 10.XXX.XXX.XXX is used for Historian connection. How did you configure the connector?

That is how it is configured 192 to SCADA ad 10. to historian.

We stopped the connector at some point thinking it might be causing the issue but no

Are all SCADA server machines in your project having dual NICs and all of them configured like

192.XXX.XXX.XXX,10.XXX.XXX.XXX in the Network Addresses field? Or you just use the machine names, not IPs. If dual NICs are just for Citect Connector, only the connector machine needs to have dual NICs and other SCADA shouldn't have any dual NICs. The problem is your webclient that is sitting on CORP network and required to directly connect SCADA servers for data requests. However, with dual NICs, the routing of IP traffic might not be desirable for SCADA applicaitons. As Eric pointed out, "Citect doesn't like to send a message on one network and receive a response from the other". A good solution is to get rid of dual NICs from server configuration as you are not using them for network redundancy and replace legacy webclient with PlantSCADA Access Anywhere.

Removed the webclient CORP IP from the project and all server processes and everything is good again. 
Not sure why its kaput in this version, was okay in the previous. Who knows, thank you for your help