One of the customers I support is seeing an issue with a site workflow that has a Call a Web Service action in a site workflow.

There are a series of Nintex workflows that communicate with an external system via Call a Web Service actions. Some workflows are list workflows that run in response to item modifications, and some are site workflows that run on scheduled jobs.

The site workflows start as expected, but when encountering the Call a Web Service function, they time out, generating an error of “Error performing web request. Unable to connect to the remote server”. The list workflows function as expected and receive responses back as expected.

I even took the site workflow and tied it to a list item, and it runs successfully, receiving a response successfully when run that way.  

I think this has to do with the app server and wfe server’s connectivity. Both servers are AWS hosted servers, and they are telling me that the app server is in a network subnet that does not allow incoming public internet traffic to reach the server. When I log in to the wfe server, and I open a web browser, I am able to go to the location of the web service. However, when I go to a web browser on the app server and I try to open the URL for the web service, I get a server unreachable error message in the web browser.

When this issue first started, I went into SharePoint Central Admin, and I stopped the “Microsoft SharePoint Workflow Timer Service” from running on the app server, and set it to only run on the WFE server. It was previously set to run on both. I assumed that this would force the scheduled site workflows to run on the WFE server. However, that did not resolve the problem. Also reset the SharePoint Timer Service, and still no change.

Anyone have any suggestions on what they can do next to resolve this problem? Networking guys are not willing at this point to move the app server into the other subnet.