How to add users in IIS Manager for an ASP.NET 4.0 application?

I have installed an ASP.NET 4.0 Web forms application in IIS 7.5. If I set the application pool to DefaultAppPool (.NET Framework 2.0) I get the icons for Providers, .NET-Roles and .NET-Users displayed on the configuration page for the application in IIS Manager and I can manage users and roles within IIS. (I’m using Forms authentication.)

Connection reset by peer (502) when contacting WCF service in IIS 7.5

We have a WCF service that has been working fine for months. Just this morning, calls to this service began failing with the proxy server reporting “connection reset by peer” (502). Oddly enough there are no IIS log entries for the dropped connections, although we are able to detect them with WireShark. So it seems as if the thread is dying, leaving no trace behind.