Thanks! I was as simple as could be and thought, that the MAC address on the back is the one to use with wlan.
However, when connecting to my wlan ín unprotected mode with no WEP or MAC filters 00 16 41 ... MAC code showed up on my wlan maintenance screen (wheras the one on the back starts with 00 16 7C ..). With WEP I didn't succeed to connect. Seems that Irex is working on wlan issues for the next software upgrade. I'll try WEP again with 2.6.