hey past me. im writing this response in case future me forgets and comes back here, a third time. or in case someone else has this issue w/ IISNode in their hosting stack.
Root Issue
we have our IIS node looking at a specific build folder, but our custom web.config was kept in the src directory and not part of the build process.
Solution
move the web.config over.
And in case your issue is on the config stuff; we had to update our location node’s system.webServer child-node to add an iisnode handler. that’s all I’ll say on the matter.