EAP-TLS Machine-Auth Windows: difference between LAN and WiFi

Hi, we're using FR 2.0 for our machine authentication for XP to Win7 with EAP-TLS. Everything is working so far, but I noticed a difference between authenticating via WLAN and LAN, which starts to be a problem for us now. If I make a auth via LAN the provided username ist <hostname>, if I do it via WLAN it is host/<hostname>. While we use "host/" as a realm for our Radsecproxy, I'd like to change the behauviour for the authentication via LAN and add a string to the <hostname> (i.e. "host/" or something else) to unify the login for WLAN an LAN. So how or where can I change that? A hint will be really welcome. TIA Alex