Make Webinterface accesible via IIS as Reverse Proxy

Hello,

im trying to make the Webinterface accessible via the windows IIS webserver, with a reverse proxy of the standalone http webinterface.
It works, but i got the “session has timed out” error if i dont click anything for only 30 Seconds or so.
That makes it really hard to use as i have to log in many times. Anybody got a working configuration for IIS?