WebSphere plugin partially working

I’m using an IIS as front-end web server and WAS 5.1 and Domino, on separated machines, as application servers (Domino runs the http task).I’ve configured the plug-in-cfg.xml file to redirect requests to WAS or (*.nsf) to Domino.

I am able to access the Domino application homepage via IIS but If I try a link it hangs.

No problem doing the same action directly on Domino http server.

Any idea ?